Reinforced 
CONCRETE 
if Factory 
Construction 


THE ATLAS PORTLAND CEMENT CO. 





‘“CONCRETE FOR 
PERMANENCRE’’ 








Reinforced Concrete 
in Factory 


Construction 


3 


Published by 
The Atlas Portland Cement Company 
30 Broad Street, New York, N. Y. 


Copyright by 
Tue Attias PorTLtanp CEMENT COMPANY 
1907, 1912, 1913, 1914, 1915 
All rights reserved. 


Eighth Edition 


NEO el ON 


Reinforced concrete has provided for the manufacturer an 
entirely new building material. Indestructible, economical and 
fireproof, it offers under most conditions features of advantage 
over every other type of construction. The development has 
naturally been greatest in the larger centers of population, but 
itis extending rapidly to the remoter districts, and, indeed, where- 
ever new buildings are contemplated. 

This widespread interest demands an authoritative treatment, 
and The Atias Portland Cement Company has embraced 
this opportunity to present to the manufacturer, and also to 
the architect and the engineer who are not concrete specialists, 
a brief treatise on reinforced concrete for factory construction, 
with a view of giving a comprehensive idea of the advantages 
and limitations of the material as adapted to the factory, anda 
demonstration of its value as illustrated in a variety of buildings 
in different localities. 

The work has been prepared by a consulting engineer, Mr. 
Sanford E. Thompson, who is well qualified to treat the sub- 
ject as an expert authority. The Atlas Portland Cement 
Company, occupying, as it does, a somewhat unique position 
among cement manufacturers, with its wide reputation for a 


thoroughly uniform and standard product, its selection by the 


I 


United States government to furnish over 5,000,000 barrels for use 
in building the Panama Canal, and its immense production—over 
50,000 barrels per day—-commends the book to its readers with the 
hope that it may prove a fitting companion volume to the other 
publications of the company described on the last page of 
this book. 


THE ATLAS PORTLAND CEMENT COMPANY. 


New York. March, 1912. 


PREFACE TO SECOND EDITION.* 


The second edition aims to cover the developments in the field of 
reinforced concrete as applied to factory construction since the appearance 
in 1907 of the first edition. 

As in the previous issue, details are presented of this type of construction 
and a careful description, with numerous illustrative drawings and photo- 
graphs, is given of typical examples of concrete buildings selected from 
various sections of the country and erected by representative builders. Sug- 
gestions are thus offered to the factory owner who contemplates building in 
reinforced concrete, while at the same time the practical details may prove 
of value to architects, engineers and builders. 

The chapter on Design and Construction has been rewritten, the chapter 
on Details of Construction has been revised and seven new chapters have 
been added, describing in detail different types of factories that have been 
built of reinforced concrete during the interval that has elapsed since the 
issue of the first edition. 

The large increase in the quantity of material has necessitated a rearrange- 
ment of the text and renumbering the pages. 

The first chapter presents to the manufacturer a brief review of the 
qualities of reinforced concrete in comparison with other materials for 
factory buildings, and this is followed by a chapter giving in considerable 
detail the general principles of design with information in regard to methods 
of construction. Chapter III treats of the selection of the aggregates. These 
general chapters are followed by sixteen chapters, each describing in full 
some one shop, factory or warehouse of reinforced concrete, selected with a 
view of presenting a variety of the more usual types of factory and warehouse 
construction. 


- *1913 Reprint of Second Edition. 


Chapter XX outlines with illustrations many of the styles and systems 
of reinforcement in common use in building construction, and briefly refers 
to examples of concrete block walls, surface finish, concrete pile foundations 
and tanks, each illustrated by photographs. 

All illustrations, excepting a part of those in Chapter XX, have been 
prepared especially for this book. The half-tones are made from original 
photographs, and the designs from drawings furnished by the engineers and 
contractors, or reproduced in the office of the author from the original plans. 
In this way a number of details are shown which seldom appear in print. 
Care has been taken throughout to give complete measurements so that the 
figures may be used as a guide to new construction work. 

The Atlas Portland Cement Company, and the undersigned, desire to 
express their appreciation of the courtesies extended by individuals and 
companies who have kindly furnished plans and data for incorporation into 
the descriptive chapters. 


SANFORD E. THOMPSON, 
March 1, 1912. Newton Highlands, Mass. 


CONTENTS 


CHAPTER I. 
Factory Construction. 

PAGE 
SOS Cia eee ea ee ean ee ee eas et Re NE Tick 2 te Ne conc tae Syshann "D4 euee 12 
AD Droxinates Gost: pete C UDICEH OOt me net arnt ar ari cise ssf ola dt ete a) oe be 12 
Saletyronereimorcedsucolcrete Construction meek earns cee ae ue eee 13 
DUT AD LAC Y ceetee: evant we seats ek eae se eae i See ais, Suche re G0) Sybian ee 13 
Teme. CS1s CAT CC aut gape mrieten ae eT Pe eae eget fee nea Se ocGit ie, «Guage ees} 14 
Ube TF he) Tokay ree a Re io On alae cn 0 Ral ra ao 2 ae ea oe 15 
ODE gece pas Gh ope cr Sb Ale ey a ate Gs, a | A enn ws 
Breecometronimy ADCAtiOl ses eee. Se ioe ey LS ne pe ne eg a 16 
VEEL Sel Uli CVMOLIND CS10 1) setters assent tema ti td aera ue. 5 “ct a Pr of 16 
OVS Tt ee ee Re eS Te eM ee eR eet Rg AE en og Pine «one ee 8 16 
WV ALTE ON LTGSS meer mn epiamen re ht nee ey ene ns neamre MP UNMET Cs art. gt ker giv a 16 
CATT CSS ere et Carn ea ae ns ere Sie ta ee oe eae iA A Gia eV as 7 
ia pidi, VeOleC ONStLUCtlOl war wre Acree trent ere Meee eis yee so ye 17 
Alteration Sameer eee reme tre erm ere eae mee ome a yee Gs kh 17 
| Te hea he O) En ES Tye pear are Gen ee oe Bg ie oN Me Mb grt Pe eas Car nie 17 
Bein oe VLACH INGLY water ch er ei are Mey Aepteaiec aa. s ae) aac oh Renee ee Oe ee sn 17 
PAU at VC DINe tl Ce aeer tc eten: teen eA ee eee RT Re te, | 18 
TACHAITICL ACL OL SemmEee ee Mere tae, he iY oe heise yh ye ce ge Ns ese Pl SVS a o> 18 
POWerE GvelODINeN Cast ser araette fete ee Peery Pein en ee ie eA. a, WS 18 
iSechmehateleksy Foe Huh hs nope oe a hae bac Lea ELMO hy eae 18 
ROO Lae ee ee Been erate Sete eee SPL LUNG hd iene Mocs bs Gala ea Rea 18 
UAT ic sour emer MO Ot Sry er vote ate) rc pu dyer «FS soo) wie ooh a1 4 ware tee we Rn ss 18 
PettinvathesGContract amar set atm fein elena a siete Baw ce hae ee 19 
Growtlsorkemiorced: Concrete: Construction wa) .s sae sea de hoe 19 
Appendix: Fire Insurance on Factories of Reinforced Concrete........ 21 

By L. H. Kunhardt. 
CHAPTER II. 
Design and Construction. 

ACCTING Cae ene eS os a's. vv ahs fo edie ord Shea mates los 24 
tices Neciicationen eimho! ands Geimen te... 05... sites cadens + oe 2 


SAM 25 siaie elekcraleve echo’ aleliece Siviake erttays cists ctOis gh cnet A Net a rte eer et eee ene 25 
Specifications-for Arpregates arcnw ony cru retn ehrer ieee eee eee 26 
Specifications: fortReinforcinge (Steele ae. ee ee ee 27 
Proportions: of) Materials737- 8) wees eee eee ee eee 28 
Machine: Mixing’ “u/s. data: 5 epee ee ae ee yr ae 28 
Consistency -5i55). cA 25g SRN caer aoa he ttn te ars Pc a ead 28 
Placitigt 5:..F 2s cto. occa hae opty Om oe tie ee eae ee eee | ee 29 
Surfaces ..062 eich ea Re on he ee eT, PE ae 29 
FOr 565.555 ststeee Sa ese ee ee ee a eee ne 29 
Foundations © 33)3s4e0 fete pic, tence sale eee Ne es ee ea 30 
Basements, Floors 3. ie. ak oc tie oee ies Oho, 2 Nee ee ira nee 32 
Design. of <Ploor *Systeni fone fae ae eee a ales re es a 32 
Columns. gin 9s fete oe 0 lows Free tao ae ee ee ee 38 
Walls elcid aay ie eee 0 inne ON 5e os eh at ene cle te 40 
Roofsi: oo cra 3 ie tee a wine eet ee en 40 
Construction: 42:i/sibces an.c oscar igs ie ie octet. oa ee 4I 


CHAPTER III. 
Concrete Aggregates. 
Effect of Different Aggregates upon the Strength of Mortar and Concrete 43 


GeneralyPrinciples tori Selecting’ Stone sna) ote eee 43 
ComparativesValues offs Differentestones ge genre ee 44 
Creneral:Principles*for, Selecting; Sande ee ee 45 
Testing Sand (a: voc hie ies ee Oe oe Oe ee 47 
Calculating Relative Strencths of sMortats.2))... sae eee 48 
Testing Concrete Agpregatess i: eer eee eee ee 49 
Proportioning: Concrete sf <5 eeeuiee ie as aetna teen ne 49 


CHAPTER IV. 
Plant of Carter’s Ink Company. 


Exterior, Design) 24.5..s sien pte oe ee es ee ee ee 51 
Reinforced..,Concretes Designee. oe es ee 51 
Foundations a... eee Too, ele: Seva ate ce ahs ah FeMERTTOA © Gus! «ja fnges thehanre See eae 54 
Cost os ssc piregtnet to Re ser ce ne! Neha ea ac ee ken 54 
CHAPTER V. 
Ketterlinus Building. 
Design... 6 sain: ahs Sew sees Dee Pe ee 55 
Coltimns. o3 wigs i's seule de gtela Sie ete, aoe ee ee he ee 59 
Column. Footings ?.. 2. 032 set ein re 60 


POOL GS Y SUCT ew c,d es Cha We ine Ta UR 61 
USCA ILS ees See a ae ee ee ne me Cente rr Moe Sue ee We, ah alae acaco Ws 63 
Val Sane, ree! haere I Aan beg. erate le Mite tars Wists (eed Mee inf OPA 63 
RODE Rasa teen eee ree eerie MAE LM Ms UR ON ek cael Ea eae tr aly. 8.38 63 
<SOTISLUUICTI ON see meee: OPO ef eA Ries ole ah Wan Rg ese ane ee Sk esos ath 64 
COSC, fit MR TM net fe SONS Rat) «we. We, (venlctea ng alenes epee ater a a rs 64 
AGISC LAI Geer eee mae tort heey ie meee Pa ier sid Boe eae ace ee 67 


CHAPTER VI. 


Maverick Cotton Mills. 


SSDI OMI LL Lope ene ee Menten ROR MER celled onthe 256 Dh. il Geka) 2 Wek 69 
WUE STS UAT LEP A Sica se neta Si i 5, byl Oo JF Sai or ee a a 72 
ORV EUM LOU SC ane ue, el ream aan Mie) Miu ERO oe 1%. Re acd, valevate one wiles 74 


CHAPTER VII. 
Lynn Storage Warehouse. 


BOO rRC OSISCUUCCI OMe mena e emer teeth, Zee s satar ete hus Gre wl gue Su yvon's chk 48 Oy ol ee 75 
MOOT DP CCILICA LIONS mater eee ie ee Par oO rors) bch eI Nes at Sasha aie ee hea, 79 
HOO Ges LLL AC C tt EEN: Bt ate ceric efor s Beis Wot seen ach eases 80 
PERE S CEC TAO Uae err eRe a tt eres. Pe oir Spat ys) fc BPS ls Sshuontrs Oke gee Behe 80 
Exe PEERS ot gle ye eee Wh As erie er aererat! Ane oie kere an ee 80 
CGS TEUIC LOU memeeNat ce acer ce tae Rn He ce rae Pe adatoe Gl eahe has Sis: Ses. one week 82 
LEU) @ISISS ~ Loak ines, Rene arene Aone Oe Monet Se 7 PR ec tah omen eh PAE Rigs te ene ee ee 85 
WAV lL CONSELUCCION nic Sepa tor tle le Pega was Cm nk ah te he Mies eS tae ys 85 
[Eva aka (olay 3X Sabet meats sp PmeRegc MS EicNer seg tig fec® 75 ark APCS Smeg aon ea 86 
WV ete OL OOLIT 9 metas en an eis et th Serene Cover, eR ode erat ar Me ct Es eens chad lek g 86 


CHAPTER VIII. 
Winchester Repeating Arms Factory. 


DESI OT seen tae tee eR te Pere seta Peau es aia cate S02 Bias LAM Ac cow a aR A od Aes 87 
GOTISCEUCTLON Meera aaa sre a Mere oe 8, con Bo, oe Loan ed Ok 2 Doe Nhca wx go 
COS tii pe tee ee Pe ee Sas Rana a dt Secs i hots + oka GWE R Dod acne 6 gI 


CHAPTER IX. 
Bullock Electric Machine Shop. 


LEYS STE pe ONE Sie i tee Se OTE eS IRE ye Reet ae pee OR at OS 93 
SOLUS Me meant re irr ame eee men eR Neate As Pei ep Ma A OT es eg 97 
CEADGEOLAGCKCL Sete. ee Sees Pee ene yt ee tints Rote a). Fn 98 


Floor System iy. face S oy aes 6 oleae Ph ek 8 he ie ee 98 
Walls. ie i 5 ech wis 555, na vedo want oP epee estar eer cu na ne 99 
Constfuction’.Planit: 6.5. 25..55, 2 en peer te aoe ee eee 100 
Gran ge Raulede fins Sunt phat OM ahem ria megs at seis ae Nea. Waser ii an tic tr ee 103 
Forms. 005 fh Be Fain seen he ae ee oe is ee ee rs 103 
CHAPTER X. 
Factory of Hunter Illuminated Car Sign Company. 
Design’ 6.9.5 sk Rate onan cert Bless opl o t ie ne ieee es oe eee 105 
Construction 52sec sik eae ee ete ce) ena aleowrer  er a Noe ea nee 105 
Oe} eC Pr Nee Ofer A cr et aes EC eS 108 


CHAPTER XI. 
Wholesale Merchants’ Warehouse. 


Layout) 2): ce bas wil oo oot ls ey RS de oI ee ene tc O2 eee eer ae 110 
Beams‘and Slabs o.e.id os fi ssten te cee ee en a eee ie Oe ee III 
Columns’ so oscc eee ie hres kaso ee oe aes ag re ere re ae 
Walls 2. cle ok a niiecd ee Shs ene ee ne 114 
Tg IO Cea. encase RNs Sin ort SPR gla dna ce II5 
Coal TreStle Aste satis ee ate Oe ae ete eae 115 
Construction —. A Melis caisitts te aioe Stet eee Rea tena ee IIS 
Cost: Sct pe bin Sb ha Wire ete oe ee ae a ete ne 122 


CHAPTER XII. 
Plant of Boston Woven Hose & Rubber Company. 


Desigtyn: bo vteyo.t nln cehoaom Ul, eqs caedyces gael to ea eats) Ue Rene eee tr es Hele 
Footings face $20 bs Gicsne sn s sea esteoneto see goketes cceeeerl, ok eiar = Ear ree ee ao ee 127 
Reinforced, Concrete” Piles 3 93 ee ee i en ne ee ee 128 
ConStruction pics ike Fe aie shee eae a ene re eek teh 129 


CHAPTER XIII. 
Bush Model Factory. 


OLS ps Ree tah Grr Or oo baer me cere ah me Gubee h bes oe Tn a oe 
Columins ois: SR, Baie ee ona a a 134 
Floor. System’ 5...) sequester Miata a area oe ee 135 
W alll so. ici soe sie Gale Guano niBi ta on te aac os) eens eee Sa 137 
Construction toi... cies 3 ates oc dee oS naan Oho te een a 137 


CHAPTER XIV. 
Packard Motor Car Factory. 


PAGE 
BLOOD OVS Celi mee Mmnn ae. eer ree cre crm eA eee Vets eS ew no S'S Sie 143 
OMIT N Seer eee eee nei eta ener nwn Wiese y rere he cet elas 4 SW lens see ele opt 147 
LET ERY ope een ete Be iss is bias ares Tee SE ea Ue ae id tt gle a ee 147 
SOUS CEU CCION mee mien rete me ty Seat gate ener Ne rake re Gas hci sats T47 
OLIN S Spee see een eters CPN t ot! etn Me me MRE oe only aha aliiaS QE ve v8 148 

CHAPTER XV. 

Warehouse of Syracuse Cold Storage Company. 

DCSIS Ngee eta wea Py I Peer he nasa Saye sale laps le ee « » ardn 153 
CCOUSCLUCTION We meg tet er enn et errr PEO I etdo oe, PS oh ole Wah Bie women y § 153 
COSI eee te Rae Se reer an ee este oof ales Aub wip ahah s a be 157 

CHAPTER XVI. 

Textile Machine Works. 

(OLUIT OS weenie errs enna et eee Oe ee ee ar red, hat re nuts. 6 natn Niele, 159 
HIOOEES Steir ee re ete eee ee ae, yl Tate, devon eee svn 0oy oe ee 162 
CO SUM rer a tenrege Pesan ORUnr. OI Se reer Tena cuter a tice Lhdja es cote) Sheen ees a kee wee wd 164 


CHAPTER XVII. 


Blacksmith and Boiler Shop of The Atlas Portland Cement Co. 


1) C512 timer me ae ale eee Rate ce iy eset te diel orate whats a Rigen Ga bye a seni acost 165 
REO RSECUCLLON mee eeet i mere the ee ge rok oid tre oat trae neta ie Sayer Le we, as 165 
Coalm Lrest eget s ei cie «oa sielegete tnuels wiciei eh wl viometetais Soha de os Bay's 0 173 


CHAPTER XVIII. 


Pierce-Arrow Motor Car Factory. 


IVEATILiE a CEUL ITO mS TL CLA) Omer memmietcn rs wel teueigc ssa Cod A ae crs ean ie 1s AE ei, PE ols 176 
PASSED ys iil Cini me eter Metre at oll neces A> onche, oie sinks ke RP Pum oie ok 177 
BOC yas alli itl Ope ret genre ee eee eee rol ert i hea reine! ake creole ata pee Henle ss 177 
StoraverandanickelPiatiiee Bull din ces rennet aa, aire pees nat inl acca 179 
(Sad Oe ee a er cstecce 6 cogMee RO CPMEA ie, wn okt s (aa alesis: kegs acocate alate Vote ays "9" va 180 
POWete ELOUS Chee tt ars SMR re ete ee tn te We de oe gene io tent Acne ft ea 180 


CHAPTER XIX. 


Pacific Coast Borax Refinery. 


PAGE 
Design. saci xe Ded GSO oa ot ee ete, Ce a cee a een emerson 181 
Propottions’ of the: Concretetemwae te ere ee 186 
Constriiction ~. oi. c¢ scp 0 b itecein here ees enh tai ee ie cetera eee 187 
The «Pires 25 cc eT ee ee SS ae hac ee 188 

CHAPTER XX. 
Details of Construction. 

Systems of Reinforcement 700... >. 46 ace en ee eee eer 193 
Factory Moldeds Concretes tater tn er 202 
Concrete -Block2:Walls isc. tc totes as ate ee ee ee ee ee 206 
Concrete? Tiles suo ea aate Base Sc Slo eee ee ee 206 
Concrete ‘Metal’: Walisi5 Gee ie oe Py Sarat a ee ene 206 
Surface. Finish 49's) Sn es sae eas ee 206 
Concrete PilerFhoundations? x0 ate toe Se ee ee 210 
Tatks or ilics 5 St tates) ne ure ER RS ee ellie bce cin eee ae acd ee 219 


MISCELLANEOUS BUILDINGS. 


CHAPTER IL. 


FACTORY CONSTRUCTION. 


A manufacturer about to build a factory or warehouse must choose be- 
tween several types of construction. In this selection the governing consid- 
erations are cost, safety, durability, and fire protection, while many minor 
factors enter into each individual case. 

In this opening chapter the qualities of the different materials available 
for factories are discussed with special reference to the reinforced concrete. 

Types of buildings for mills, factories, and warehouses may be classified 
as follows: 

(1) Frame construction; 

(2) Steel construction; 

(3) Mill or slow burning construction; 

(4) Reinforced concrete construction. 

The first and cheapest type of frame construction may be neglected as 
unsuitable for permanent installation because of its lack of durability and its 
fire risk. Board walls, narrow floor joists, board floors and roofs, not only do 
not protect against fire, but in themselves afford fuel even when the contents 
of a factory are not combustible. 

Steel construction with concrete or tile floors, provided the steel is itself 
protected from fire by concrete or tile, is efficient and durable, but its first 
cost alone will usually prohibit its use for the ordinary factory building. 

Mill, or “slow burning” construction, as it is sometimes called to dis- 
tinguish it from fireproof construction, consists of brick, stone, or concrete 
walls, with wooden columns, timber floor beams and thick plank floors, which, 
although not fireproof, are all so heavy as to retard the progress of a fire and 
thus afford a measure of protection. 

Reinforced concrete, through the reduction in price of first-class Port- 
land cement and the greater perfection of the principles of design, has lately 
become a formidable competitor to both steel and slow burning construction, 
a competitor of steel, not only for factories and warehouses, but also for office 
buildings, hotels and apartment hottses, because of its lower cost, shorter 
time of construction, and freedom from vibration; a competitor of slow 
burning construction because of its greater fire protection, lower insurance 
rates, durability, freedom from repairs and renewals, and even in many cases, 
its lower actual cost. 


qI 


COST. 


As a fundamental principle in mill and factory construction, the cost 
must be such that the outlay for interest on construction, running expenses, 
and maintenance, shall be at the lowest possible minimum consistent with 
conservative design and the requirements of operation. A wooden building is 
cheap in first cost, and therefore in interest charges, but is expensive in in- 
surance and repairs, while the risk of the loss in production after a fire, for 
which no insurance provides, may far counterbalance any theoretical saving. 

As a general proposition, reinforced concrete is almost invariably the 
lowest priced fireproof material suitable for factory construction. The cost 
is nearly always lower than that for brick and tile, and with lumber at a 
high price, it is frequently even lower than brick and timber, with the added 
advantage of durability and fire protection. 

In comparing the cost of different building materials, one must bear in 
mind that the concrete portion of the building is only a part of the total cost. 
Since the cost of the finish and trim may equal or exceed that of the bare struc- 
ture, even if the concrete itself cost, say, 10 per cent. more than brick and tim- 
ber, the cost of the building complete may not be 5 per cent. greater than with 
timber interior. The lower insurance rates will partly offset this even if there 
is no other economical advantage for the fireproof structure. 

The exact cost of a building in any case is governed by local conditions. 
In reinforced concrete, the design, the loading for which it must be adapted, 
the price of cement, the cost of obtaining suitable sand and broken stone or 
gravel, the price of lumber for forms, the wages of the laborers and carpenters, 
are all factors entering into the estimate. Reinforced concrete is largely laid 
by common labor, so that high rates for skilled laborers affect it less than many 

other building materials. 


APPROXIMATE COST PER CUBIC FOOT. 


As a general proposition, it may be stated that the cost of reinforced con- 
crete factories finished complete with heating, lighting, plumbing, and eleva- 
tors, but without machinery may run, under actual conditions, from 8 cents 
per cubic foot of total volume measured from footings to roof, to 12 cents per 
cubic foot. The former price may apply where the building is erected simply 
for factory purposes with uniform floor loading, symmetrical design—permit- 
ting the forms to be used over and over again—and with materials at moderate 
prices. Several of the buildings of simple design described in the chapters 
which follow come in this class. The higher price will usually cover such a 
manufacturing building as the Ketterlinus, described in Chapter V, located in 
a restricted district, and where the appearance both of the exterior and interior 
must be pleasing. This does not include in either case interior plastering or 
partitions. 


12 


SAFETY OF REINFORCED CONCRETE CONSTRUCTION. 


In any type of building there is more or less danger of accident during erec- 
tion. It may be stated, however, that with ordinary skill in design and con- 
struction there is no more liability of failure with reinforced concrete than 
with other structural materials. Accidents which have occurred can be traced 
invariably to a disregard of elementary principles of design or construction. 

Every little while failures of steel structures occur through neglect of such 
details as proper riveting, sufficient bracing, or competent design. Even brick 
buildings are by no means immune from accidents through poor workmanship 
or ignorance. For example, on a single night in the spring of 1905, the walls 
of several apartment houses in process of building in different parts of New 
York City fell down, the cause being undoubtedly the freezing and thawing of 
the mortar. Yet one does not condemn either steel or brick as a building ma- 
terial. Such failures, whether in steel, brick or concrete, have simply empha- 
sized the fact, and it cannot be too strongly insisted upon, that a thorough 
knowledge of the theory of design is essential as well as experience and vigil- 
ant inspection during erection. 

For reinforced concrete buildings it is especially important that the de- 
signer be competent, and that the builder be of undoubted experience and with 
a knowledge of the fundamental principles of this particular type of construc- 
tion. By this it is not meant that the builder be an expert mathematician, but 
he should be able to recognize the necessity for placing the steel near the bot- 
tom surface of the beams and slabs, of accurately placing all the steel exactly 
as called for on the plans, uniform proportioning of the concrete, of break- 
ing joints at the proper places, of laying beams and slabs as a monolithic 
floor system, and of determining the hardness of the concrete before removing 
forms and shores. 

The safety of a well designed reinforced concrete building increases with 
age, the concrete growing harder and the bond with the steel becoming 
stronger. 


DURABILITY. 


There is scarcely any class of manufacture which is not now being carried 
on in a reinforced concrete building. It is adaptable to any weight of loading, 
to high speed and heavy machinery, as well as to light machine tools, and 
to almost any style of design. 

Recent scientific experiments, as well as actual experience, are favorable 
to the use of concrete under repeated and vibrating loads. 

The use of concrete in brackets for supporting crane runs, as in the Bul- 
lock shop, Chapter IX, is an interesting example of severe application of load- 
ing. Several concrete buildings in San Francisco withstood the shock of the 
earthquake, while those around them of brick and stone and wood were 
destroyed. 


13 


While most materials tend to rust or decay with time, concrete under proper 
conditions continues to increase in strength for months or even for years. 

Concrete expands and contracts with changes of temperature. Its co- 
efficient of expansion, that is, its expansion in a unit length for each degree of 
increase in temperature, is almost identical with steel, and on this account 
there is no tendency of the steel to separate from the concrete, and they act 
together under all conditions. As in building with other materials, prevision 
must be made in long walls or other surfaces for the expansion and contraction 
due to temperature, by placing occasional expansion joints or by adding extra 
steel. In factories of ordinary size, no special provision need be made, as the 
regular steel reinforcement will prevent cracking. 

Special precautions are necessary for laying concrete in sea water. A 
first class cement must be selected, rich proportions used—at least 1:2:4—a 
coarse sand, and well proportioned aggregate which will produce a dense im- 
pervious mass. 


FIRE RESISTANCE. 


Reinforced concrete ranks with the best fireproof materials, and it is this 
quality perhaps more than any other which is responsible for the enormous 
increase in its use for factories. 

Intense heat injures the surface of the concrete, but it is so good a non- 
conductor that if sufficiently thick, it provides ample protection for the steel 
reinforcement, and the interior of the mass is unaffected even in unusually 
severe fires. 

For efficient fire protection in slabs, under ordinary conditions the lower 
surface of the steel rods should be at least 34 inch above the bottom of the slab. 
-In beams, girders and columns, a thickness of 114 to 21% inches of concrete 
outside of the steel, varying with the size and importance of the member, and 
the liability to severe treatment, is in general sufficient. In columns, whose 
size is governed by the loads to be sustained, an excess of sectional area should 
be provided so that if, say, 1 inch of the surface is injured by fire, there will 
still be enough concrete to sustain any loads which may subsequently come 
upon it. 

One of the advantages of concrete construction as a fireproof material is 
that the design may be adapted to the local conditions. For example, in an 
isolated machine shop where scarcely any inflammable materials are stored, 
it is a waste of money to provide a thick mass of concrete simply to resist fire. 
On the other hand, for a factory or warehouse storing a product capable of 
producing not merely a hot fire—a hot short fire will not damage seriously— 
but an intense heat of long duration, special provision may be made by using 
an excess area of concrete perhaps two or three inches thick. 

Actual fires are the best test of a material. One of the most severe on 
record occurred in the Pacific Coast Borax Refinery described in Chapter XIX, 
and the concrete there, as well as in the Baltimore and San Francisco fires, 
made an excellent record. 


14 


The best fire resistance materials for concrete are first-class Portland 
cement with quartz sand and broken trap rock. Limestone aggregate will not 
stand the heat so well as trap, while the particles of gravel are more easily 
loosened by extreme heat. Neither of these materials, however, if of good 
quality, need be rejected for building construction unless the demands are 
especially exacting and the liability to fire great. Cinders make a good aggre- 
gate for fire resistance, but the concrete made with them is not strong enough 
for reinforced concrete construction except in slabs of short span or in par- 
tition walls. 

The fire resistance of concrete increases with age, as the water held in the 
pores is taken up chemically and is evaporated. 


INSURANCE. 


When reinforced concrete first came to the front for factories and ware- 
houses, the insurance companies hesitated to assume such buildings as first- 
class risks. However, examination and tests have gradually convinced the 
most skeptical of their true fire resistance, until now structures of this mate- 
tial are sought after and given the lowest rates of insurance. 

Mr. L. H. Kunhardt, Vice-President and Engineer of one of the oldest of 
the Factory Mutual Insurance Companies, which have for years played a lead- 
ing part in the development of mill construction, and the science of fire pro- 
tection engineering and the consequent reduction of fire losses, presents in an 
Appendix to this chapter (p. 21) very instructive figures comparing the costs 
of insurance upon several types of factories for various classes of manufacture. 
Mr. Kunhardt also indicates the means by which concrete may be utilized in 
reducing even the present low rates of insurance upon buildings protected by 
efficient fire apparatus. 

From the statements there given by so eminent an authority on mill in- 
surance, we may conclude that a well-designed reinforced factory with con- 
tinuous floors (1) offers security against disastrous fires and total loss of 
structure; (2) reduces danger to contents by preventing the spread of a fire; 
(3) prevents damage by water from story to story; (4) makes sprinklers un- 
necessary in buildings whose contents are not inflammable; (5) reduces danger 
of panic and loss of life among employees in case of fire. 


STIFFNESS. 


A reinforced concrete building really resembles a structure carved out of 
a single block or solid rock. It is monolithic throughout. The beams and 
girders are continuous from side to side and from end to end of the building, 
while even the floor slab itself forms a part of the beams, and the columns 
are also either coincident with them or else tied to them by their vertical steel 
rods. 

All this accounts for the extraordinary stiffness and solidity of a rein- 
forced concrete structure, and differentiates it from timber construction where 


15 


positive joints occur over every column; and even from steel construction, in 
which the deflection is greater. 


FREEDOM FROM VIBRATION. 


This solidity and entire lack of joints, and particularly the weight of the 
material, especially adapts it to both high speed and heavy machinery. The 
vibrations are deadened and absorbed in a way which is impossible in steel 
structures. 

An interesting example of this fact is furnished in the Ketterlinus building 
described in Chapter V, where the vibration and jar in the new concrete 
building are remarkably less than in the adjacent steel and tile structure carry- 
ing the same type of machinery. 


VERSATILITY OF DESIGN. 


Steel rods are set in the concrete, to provide tensile strength, in such 
quantity and location as is needed for special loading for which it is designed. 
Consequently, spans can be constructed of any reasonable length, either long 
or short, and column spacing may be adapted to the requirements of operation. 
Because of the weight of the concrete, which must itself be borne by the 
strength of the member, very long beam and girder spans are relatively more 
expensive than the more ordinary spans of 15 or 20 feet. Similarly, the cost 
of floor slabs per square foot increases appreciably with their span. These 
limitations are economical rather than theoretical, and every design should 
therefore be studied thoroughly to produce the best results at least cost, and 
to adapt the structure to the class of manufacture or storage for which it is 
intended. 

The rule applies to reinforced concrete as well as to other structures, that 
the industrial portion of the plant, the arrangement of the machines, and of the 
transmission machinery, should be first designed and the structure adapted 
to give a minimum operating expense. 


LIGHT. 


A special feature of reinforced concrete construction is the possibility of 
building practically the entire wall of glass, so as to afford a maximum amount 
of light. Concrete is so strong that the columns can be made of small size 
and the windows carried by shallow beams. The window area may thus 
cover a very large percentage of the wall surface. 


WATERTIGHTNESS. 


In some classes of manufacture where water is freely used, as in paper 
and pulp mills, it is essential that the floors shall be tight so that water cannot 
fall into the product on the floor below or on to the belting. In case of fire 
a watertight floor prevents damage from water to the machinery and materials 


16 


in the stories below. A concrete floor with granolithic surface is practically 
impervious to water. 
CLEANLINESS. 


Concrete floors may be laid on a slight slope with a drain along the sides 
of the room so as to carry off all water and permit flushing with the hose. 
Concrete is vermin proof. 


RAPIDITY OF CONSTRUCTION. 


The speed with which a reinforced concrete building can be completed is 
due in a great measure to the fact that there need be no waiting for materials. 
Sand and stone are always available; Portland cement is now supplied by large 
mills with immense storage capacity; and steel rods are kept in stock, so that 
a building can be commenced as soon as the plans are completed and no de- 
lays need be incurred in ordering special shapes and awaiting their shipment 
from the mills. 

In general under good superintendence the rate of progress of a reinforced 
concrete factory may be as fast as one-half story or even one story per week. 


ALTERATIONS. 


Reinforced concrete is not suitable for a temporary structure. It is too 
difficult a matter to tear it down. Radical changes in construction are not 
readily made, but holes may be cut in walls and floors at greater expense than 
in wood, but without serious difficulty. 


HANGING SHAFTING. 


Provision may be made for shafting by placing bolts or sockets in the 
beams to connect with pillow blocks for special lines of shafting, or such con- 
nections may be made at regular intervals so that timbers or steel frames may 
be bolted and shafting, or tracks for conveying material, supported at any 
positions subsequently specified. 


BEDDING MACHINERY. 


All ordinary machinery can be directly bolted to the concrete floors by 
drilling holes into them and setting lag-screws or through-bolts. If a concrete 
foundation is built for a special machine or engine, it may be bedded directly 
upon the concrete. To level the machine on a permanent base, it may be 
leveled an inch or two above the foundation proper and grouted. A dam of 
sand is built around the machine, and grout, made of Portland cement mortar 
in proportions one part cement to one or two parts of sand mixed to the con- 
sistency of thick cream, is poured into it so as to run under the casting, and 
then as this mortar hardens it is continually rammed with a rod to prevent 
shrinkage and form a solid, permanent base. 


17 


AUXILIARY EQUIPMENT. 


Not only the factory itself, but many of its accessories are built of con- 


crete. 
FOUNDATIONS. 


Foundations for engines, boilers and heavy machines are of course made 
of concrete, this being customary long before its introduction for building 
construction. The method of setting and bedding machinery has been re- 
ferred to in a preceding paragraph. 


POWER DEVELOPMENT. 


Dams either of plain gravity section or of reinforced designs, flumes, pen 
stocks and wheelpits, are all built of this material. Every individual develop- 
ment requires a special design. 


PARTITIONS. 


In the factory itself, partitions may be made of reinforced concrete walls 
four inches thick, or of concrete blocks, as in the Wholesale Merchants’ Ware- 
house at Nashville, Tenn., described in Chapter VIII. For solid partition 
walls and elevator wells, it is convenient to pour the concrete after the floors 
are laid, and this may be done according to the plan adopted by the Turner 
Construction Company in the Bush Model Factory No. 2 (see Chapter IX), 
by leaving a slot in the floor at the proposed location for the partition. 


ROOF. 


Naturally, the roof of a reinforced concrete building is of the same mate- 
rial, designed to carry the weight of roof covering and snow which may come 
upon it. It is advisable to cover with some form of roofing, as the sun beating 
down upon the concrete surface will tend to crack it. 

If the building is erected with a view to adding one or more stories, it is 
well to build the roof of wood or light steel construction so that it may be 
readily taken down or raised. 

TANKS. 


The making of durable tanks is one of the problems in many factories. 
This is being solved in numerous cases by the use of reinforced concrete, de- 
signed with sufficient steel to resist the water pressure. In paper and pulp 
mills the adoption of concrete tanks is especially advisable because of the 
frequent repairs and renewals required in wood construction. Special at- 
tention should be given to the watertightness of concrete by grading all the 
aggregates and by care in placing. 

The concrete in a tank should be poured in one continuous operation 
so as to avoid joints, which are liable to leak. Enough circular steel must be 


18 


provided to resist the entire pressure of the liquid when the tank is full. 
The stress on steel under this pressure should not exceed 12,000 pounds per 
square inch.* 


LETTING THE CONTRACT. 


The contract for the construction of a reinforced concrete factory should 
be let only to responsible builders with practical experience in this class of 
work. A man who has simply laid concrete foundations is not competent to 
erect a factory building. This matter of experience cannot be too strongly 
emphasized, since every one of the failures in reinforced concrete can be traced 
directly to poor design or to an ignorance and disregard on the part of the 
builder of the fundamental principles of reinforced concrete construction. 

If day labor is employed, as in the case of the Textile Machine Shop, 
Chapter XI, it must be under the direct superintendence of an engineer skilled 
in concrete construction. 

The plan is frequently followed of requesting estimates from different 
contractors without specifying the requirements of the design. As a con- 
sequence, the man who dares to figure with the smallest factor of safety, and 
who thus would build the poorest and weakest structure, presents the lowest 
bid. Such a possibility may be precluded by having at least the general plans 
and specifications prepared in advance by a competent engineer or architect, 
so that the estimates may be compared with fairness. 

Concrete building construction is frequently performed on the cost-plus- 
a-fixed-sum of cost-plus-a-percentage-basis. These methods are apt to result 
in a somewhat higher cost for the structure than competitive bidding, although 
they offer less temptation to the builder. 

Whatever plan is followed, one or more competent inspectors should be 
employed by the owners independent of the contractor to see that the work 
is properly performed in all its details. 


GROWTH OF REINFORCED CONCRETE CONSTRUCTION. 


One of the first uses of reinforced concrete in building construction was 
in the house erected by W. E. Ward in 1872 at Port Chester, N. Y. Some 
twenty years earlier than this, in France, the first combinations of iron im- 
bedded in concrete were made in a small way. However, not until the very 
end of the last century, since 1895, has concrete been employed commercially 
in the construction of buildings. Previously to this it had attained a wide use 
in foundations, and at this time its development was beginning for suck 
structures as dams, sewers and subways. 

Two principal reasons may be offered for this comparatively slow growth 
followed by such marvelous activity. In the first place, Portland cement 
manufacturers, beginning in Europe about the middle of the 19th century and 

*Thickness of concrete for tanks and reinforcement for different diameters and heights is given in “‘Con- 


crete Construction About the Home and on the Farm,” published by The Atlas Portland Cement Co., copy of 
which will be sent on request. 
19 


in the United States about 1880, finally produced a grade of cement which, 
with the inspection necessary for all structural materials, could be depended 
upon to give uniform and thoroughly reliable results; furthermore, along with 
the perfection of the process of manufacture, the price gradually fell from the 
high cost per barrel in 1880 for imported cement, to a figure for domestic 
Portland cement of equally good, if not better, quality, at which concrete in 
plain form could compete with rough stone masonry, and with steel imbedded 
could compete with other building materials. 

In the second place, theoretical studies and practical experiments have 
now produced rational and positive methods for computing the strength of 
concrete reinforced with steel so that absolute dependence can be placed 
upon it. 

A conservative estimate places the number of reinforced concrete build- 
ings built in the United States during the year 1906 as not less than two hun- 
dred, while at least as many more have gone up in concrete blocks and com- 
binations of concrete with other materials. 

Briefly, reinforced concrete such as is used for factory construction con- 
sists of Portland cement, sand, and gravel or broken stone, mixed with water 
to a consistency that will just flow sluggishly, and in which steel rods are im- 
bedded so as to produce an artificial stone with many characteristics of steel. 

In the earlier stages of reinforced concrete and even up to the present 
time, many patents of a more or less fundamental character have been granted. 
These have taken the line of special forms of reinforcing metal as well as 
methods of design. The principal styles of reinforcement are illustrated in 
Chapter XX. While it is not necessary to encroach on any of these inven- 
tions in building, the field is worth careful consideration, from the viewpoint 
of economy and durability, as to whether or not it may be advisable to make 
use of them. 


20 


APPENDIX. 


FIRE INSURANCE ON FACTORIES OF REINFORCED CONCRETE. 
By L. H. Kunhardt, Vice-President. 


Boston Manufacturers’ Mutual Fire Insurance Co. 


In consideration of the question of insurance on reinforced concrete fac- 
tories, the problem simply resolves itself into a determination of what the fire 
and water damage will be in the event of fire compared with that in other 
types of factory buildings. 

For this purpose concrete factories may be divided into two classes: 

1st. Those having contents which are not inflammable or readily com- 
bustible. In this class, if wooden window frames and partitions, etc., have 
been eliminated, the building as a whole becomes practically proof against 
fire, provided there are no outside exposures, protection against which would 
require special precautions. 

2nd. Those having contents which are more or less combustible, and 
which have in their construction small amounts of inflammable material, such 
as wooden window frames and top floors. In this class the burning of con- 
tents is the cause of damage to the building, the extent of which is deter- 
mined by the character of the contents. 

Of the two, the latter class is the one ordinarily met, and with which the 
question of insurance cost is therefore usually concerned. The character of 
the occupancy, details of construction and conditions of various kinds inside 
and outside the factory, and in the various communities, have such direct 
bearing on rates that any statement as below of comparative cost must be 
extremely approximate, but perhaps of value as showing somewhat the relative 
costs. These in the following table are made upon the basis of a building with- 
out a standard fire equipment, which condition is, however, now rare in the 
case of first-class factories and warehouses, even if of fireproof construction. 


CONCRETE FACTORIES VS. THOSE OF WOOD OR BRICK. 


Approximate Yearly Cost of Insurance Per $100. 
Exposures, none; area not large; good city department; no private fire 
apparatus except such as pails and standpipes. 
Add for Brick or 
Wood Buildings in 


Brick Mill Con- Wood Mill Con- Small Towns and 
struction or Open struction or Open Cities Without 


All Concrete. Joists. Joists. Best of Water and 
Bldg. Contents. Bldg. Contents. Bldg. Contents. Fire Departments. 
General Storehouse............. 20c. 45c. 60c. 100c. 100c. 125c. 25c. 
Wool Storehousey..o.. sue. oe 20c. 35c. 40c. 60c. T5c. 100c. 25c. 
Office Building“). -ca:@ Emenee 15c. 30c. 35c. 50c. 100c 125c. 25c. 
Cotton) Pactorysa2...ce ci -1steeet 40c. 100c. 100c. 200c. 200c. 300c. 50c. 
Tannery.ce).2 Secs are be ees 20c. 40c. Tic. 100c. 100c. 100c. 25c. 
Shoe FactOryec.cccrscesien ss ene 25c. 80c. 7T5c. 100c. 150c. 200c. 50c. 
Woolen Mill oo ot ctierescneranenstores 30c. 80c. 75c. 100c. 150c. 200c. 50c. 
Machine SHOpsejxes pees cine ate 15c. 25c. 50c. 50c. 100c. 100c. 25c. 


General Mercantile Building. ... 365c. 75c. 50c. 100c. 100c. 150c. 25c. 
Note.—tThese costs are based on the absence of automatic sprinklers and other private fire protective 

appliances of the usual completely equipped building. They are not schedule rates, but may be an approxi 

mation to actual costs under favorable conditions based on examples in various parts of the country. 


21 


The table in a general way illustrates the gain by the use of the better 
type of construction, but in factory work it has long been recognized that 
there is a distinct hazard in the manufacturing operations and inflammable 
contents which is greater in degree than in other classes of property. The 
science of fire protection with automatic sprinklers and auxiliary apparatus 
has therefore attained such a degree of perfection that the brick or stone fac- 
tory with heavy plank and timber floors is obtaining insurance at rates which 
are lower than those which are possible on any of the fireproof buildings 
without sprinklers. The real reason for this lies in the fact that the contents, 
including machinery, stock in process, and finished goods, constitute by far 
the larger part of the value of the plant, and these the building alone cannot 
be expected to protect when a fire occurs within, except in so far as the ab- 
sence of combustible material in construction may assist in so doing. Fire 
protection is therefore needed for safety of contents, even if the building itself 
is practically fireproof. 

As illustrating the value of fire protection, I would state that in the Boston 
Manufacturers’ Mutual Fire Insurance Company, and others of the older of 
the Factory Mutual Companies, the average cost of insurance on the better 
class of protected factories has now for some years averaged, excluding inter- 
est, less than seven (7) cents on each one hundred dollars of risk taken, and 
on first-class warehouses connected with them, one-half this amount. These 
figures can be compared with the table as illustrating the gain by the installa- 
tion of proper safeguards for preventing and extinguishing fire. 

In these same protected factories and warehouses the actual fire and water 
loss is less than four (4) cents on each one hundred dollars of insurance, and, 
being so small, it would seem that they must be almost impossible of reduc- 
tion, but nevertheless it is possible. 

How can this be accomplished? This is the problem of the designer and 
builder of the concrete factory. 

Ist. By avoiding vertical openings through floors—a common fault in 
many factories with wooden floors. To bea perfect fire cut-off, a floor should 
be solid from wall to wall, with stairways, elevators and belts enclosed in 
vertical fireproof walls having fire doors. 

2nd. By provision for making floors practically waterproof, that water 
may not cause damage on floors below that on which fire occurs. Scuppers 
of ample size to carry water from floors to outside are an essential part of the 
design. In the ordinary factory with wooden floors, loss from water is almost 
invariably excessive as compared with the loss by actual fire. 

3rd. By making the buildings as incombustible as possible, thus re- 
ducing the amount of material upon which a fire may feed. Also by provision 
for sufficient thickness of fireproofing to thoroughly insulate all steel work, 
the fireproofing being sufficiently substantial that it may not scale off ceilings 
or columns at a fire or from other causes, thus allowing failure of steel work, 
by heating or deterioration. An owner is thus more secure if the fire protec- 
tion or any parts of it fail at a critical moment. 


22 


4th. By good judgment as to the extent or amount of fire protection re- 
quired in each individual case. While the value of the automatic sprinkler 
is recognized and the general rules specify its installation, the Factory Mutual 
Companies do not require it in the concrete building, except where there is 
sufficient inflammable material in the contents to furnish fuel for a fire. An 
essential feature of good factory construction includes not only consideration 
of the building, but protection adequate to its needs only. 

The extent to which the above is faithfully carried out will eventually be 
the determining feature in the cost of insurance. 


January 1, 1912. 


23 


CHAPTER IL 


DESIGN AND CONSTRUCTION. 


Concrete is an artificial stone, and if it contains no steel, that is, if it is 
not reinforced, it is brittle like stone. Just as stone can be used to support 
enormous loads, as in foundations, bridges and dams, provided it is so placed 
as to receive no tension or pull, so can concrete stand heavy loading in com- 
pression with no reinforcement. 

Concrete, however, has the advantage of stone, because when built in 
place, steel, which is especially adapted for withstanding pull, may be intro- 
duced at just the right position in the beam or other member to take this pull. 
In an ordinary beam the upper surface is in compression and the lower sur- 
face in tension; the natural arrangement of materials is therefore to design 
the beam so that the upper part is composed of concrete, which takes the 
compression, while steel is embedded near the bottom to resist the pull or 
tension. The concrete by surrounding the steel protects it from rust and 
fre, and because concrete and steel expand and contract almost exactly alike 
when heated and cooled, they may be used thus in combination with no 
danger of separation from changes in temperature. 

It is evident that to make a safe combination of concrete and steel it is 
necessary to know just how much load each can stand, and just where the 
steel must be located to take every bit of the tension which may occur in any 
part of the beam. While in a beam supported at the ends the pull is in the 
bottom and the principal steel must be as near to the bottom as is consistent 
with rust and fire protection, on the other hand, when the beam is built into 
a column or into another beam, a load upon it produces also a pull at the top 
of the beam over its supports which tends to crack it there. Furthermore, 
there are other secondary stresses in the interior of the beam, partly shear 
or tendency to slide and partly tension or pull, which must be guarded against 
by locating steel rods in the proper places. Hence the necessity, because of 
the complication in the action of the stresses even in a simple beam, that the 
designers have a knowledge of the principles of mechanics and the theories 
involved. 

It is not the purpose of this book to dwell upon the theory of design, but 
instead to give practical principles of construction to supplement the theory 
which can be obtained readily from other sources. 


CEMENT. 


Portland cement should always be used for concrete building construc- 
tion because it is not only stronger than natural cement but is more reliable 
and hardens more quickly. 


24 


The standard specifications adopted by the American Society for Test- 
ing Materialst are generally adopted for important work throughout the 
country. Brief specifications may be sufficiently comprehensive for work of 
minor importance. 


BRIEF SPECIFICATIONS FOR PORTLAND CEMENT. 


A cement shall be a first-class Portland cement of a standard brand 
bearing a good reputation, sound—i. e., not liable to expansion or disintegra- 
tion—fine and of uniform quality. It shall be free from lumps and shall be 
packed in sound barrels, or, if stored in a dry place to be used immediately, 
it may be packed in stout cloth or canvas bags. 


Specific Gravity.*—The specific gravity of the cement, ignited at a low 
red heat, shall not be less than 3.10 and the cement shall not show a loss 
on ignition of more than 4 per cent. 

Fineness.*—It shall leave by weight a residue of not more than 8 per 
cent. on the No. 100, and not more than 25 per cent. on the No. 200 sieve. 

Time of Setting.*—It shall not develop initial set in less than 30 minutes 
and must develop hard set in not less than 1 hour nor more than to hours. 

Tensile Strength.*—The minimum requirements for tensile strength 
for briquettes 1 square inch in cross-section shall be as follows, and the 
cement shall show no retrogression in strength within the periods specified: 


Neat Cement. 


Age. Strength. 

SACIIOUL SHIN IULOIS tea lle ier einen Rete teens «Che tne eee 175 pounds 

7 days (1 day in moist air, 6 days in water)........ 500 i 
28 days (1 day in moist air, 27 days in water)........ 600 - 

One Part Cement, Three Parts Standard Ottawa Sand. 

7 days (1 day in moist air, 6 days in water)........ 200 iF: 

28 days (1 day in moist air, 27 days in water)........ 275 My 
SAND. 


Since it is impossible for even the most expert engineer to determine 
positively by inspection whether or not a sand is fit to be used in concrete, 
it is absolutely necessary that it should be tested for important work. 

The difficulty is that the impurities, while affecting the chemical com- 
bination with the cement, may be so minute as to be impossible to distinguish 
by the eye. 

An extremely small percentage of vegetable matter of certain kinds 
may delay the hardening of the cement so that at seven days there is prac- 
tically no strength in the concrete or mortar. 

+ These may be obtained by addressing The Atlas Portland Cement Company. 


* Paragraphs designated thus are quoted from the Standard Specifications of the American Society tor 
Testing Materials. 


25 


Sand which contains impurities can sometimes be used by special treat- 
ment. In some cases it can be washed satisfactorily by constructing a 
Special apparatus, such as a box containing perforated pipe through which 
water is forced under pressure so that the silt rises to the surface and flows 
off with the surplus water, while the washed sand may be drawn off through 
a gate at the bottom. 


SPECIFICATIONS FOR AGGREGATES. 


The following specifications are of so general a character as to be 
applicable to nearly all kinds of concrete construction. 

Fine Aggregates.*—The fine aggregate shall consist of sand, crushed 
stone or gravel screenings passing when dry a screen having '%-inch 
diameter holes, or a screen having 4 meshes to the linear inch. It shall 
be clean, coarse and free from vegetable loam and other deleterious matter. 
A gradation of the size of grain is preferred. Mortars composed of 1 
part Portland cement and 3 parts fine aggregate, by weight, when made 
into briquettes, shall show a tensile strength of at least 70 per cent. of the 
strength of 1:3 mortar of the same consistency made with the same cement 
and standard Ottawa sand. To avoid the removal of any coating on the 
grains which may affect the strength, bank sands shall not be dried before 
being made into mortar, but shall contain natural moisture. The percentage 
of moisture may be determined upon a separate sample for correcting weight. 
From Io to 40 per cent. more water may be required in mixing bank or arti- 
ficial sands than for standard Ottawa sand to produce the same consistency. 

Coarse Aggregates.*—The coarse aggregate shall consist of inert material, 
such as crushed stone or gravel, which is retained on a screen having 14-inch 
diameter holes. The particles shall be clean, hard, durable, and be free 
from all deleterious matter. Aggregates containing soft, flat or elongated 
particles should be excluded from reinforced concrete. A gradation of sizes 
of the particles is advantageous. The maximum size of the coarse aggregate 
shall be such that it will not separate from the mortar in laying and will 
not prevent the concrete fully surrounding the reinforcement or filling all 
parts of the forms. Where concrete is used in mass the size of the coarse 
aggregate may be such as to pass a 3-inch ring. For reinforced concrete a 
size to pass a I-inch ring or a smaller size may be used. 

Gravel.*—The gravel shall be composed of clean pebbles free from 
sticks and other foreign matter and containing no clay or other material 
adhering to the pebbles in such quantity that it cannot be lightly brushed 
off with the hand or removed by dipping in water. It shall be screened; to 
remove the sand which shall afterwards be remixed with it in the required 
proportions. 


* Paragraphs designated by an asterisk are quoted with permission from Taylor & Thompson’s “Concrete, 
Plain and Reinforced,’ Second Edition. 

7In exceptional cases where the relation of pebbles to sand is very uniform, the mixture of sand and 
pebbles may be used without screening. Frequent tests shall then be made to see that the proportions of 
the coarse and fine grains are correct. 


26 


Broken Stone.*{—The broken or crushed stone shall consist of pieces 
of hard and durable rock, such as trap, limestone, granite, or conglomerate. 
The dust shall be removed by a sand screen, to be afterwards, if desired, 
mixed with and used as a part of the sand, except that if the product of the 
crusher is delivered to the mixer so regularly that the amount of dust, as 
determined by frequently screening samples, is uniform, the screening may 
be omitted, and the average percentage of dust allowed for in measuring 
the sand. 


Water.*—The water shall be free from oil, acid, strong alkalies, or vege- 
table matter. 


SPECIFICATIONS FOR REINFORCING STEEL. 


There is frequently a question as to the use of high or low-carbon steel. 
High-carbon steel is very apt to be brittle unless it is made so as to pass rigid 
specifications such as are given below, in which case it can be depended upon, 
and owing to its greater strength will be more economical than ordinary 
merchant steel. Steel with high elastic limit and deformed section is espe- 
cially good for temperature reinforcement. 


*MEDIUM OR LOW-CARBON STEEL for reinforcement shall have 
an ultimate tensile strength of 55,000 to 65,000 pounds per square inch, an 
elastic limit of not less than one-half the ultimate strength (i. e., not less than 
27,000 pounds), and a minimum elongation in 8-inch of 1,400,000 divided by 
the ultimate strength per cent. The fracture shall be silky. Test specimens 
for bending shall be bent cold to 180 degrees flat without fracture. 


*“RIRST-CLASS OR HIGH-CARBON STEEL shall conform to follow- 
ing specifications: 


Chemical Properties: 


Phosphorus shall not exceed 0.06 
Sulphur pn Se Ms 0.06 
Manganese “ . a 0.80, or be below 0.40 


Physical Properties: 


Tensile strength in pounds per square inch shall be not less than 85,000. 

Yield point in pounds per square inch shall not be less than 52,500. 

Elongation per cent. in 8-inch shall not be less than 1o. 

For material more than 34 of an inch in thickness, a deduction of 1 per 
cent. shall be made from the specified elongation for each increase of ¥g inch 
in thickness above 3% of an inch. 


* Paragraphs designated by an asterisk are quoted with permission from Taylor & Thompson’s ‘‘Con- 
crete, Plain and Reinforced,’’ Second Edition. 

he maximum size of stone for building construction is customarily limited to 1 inch or 1% inches, so 

that the cencrete may be carefully placed around the steel and into the corners of the forms. In certain 

cases %-inch or %-inch stone is specified, but the larger size is better, provided it can be properly placed. 


27 


Bending Test: 


Test specimens for bending shall be bent cold to the following angles 
without fracture on the outside of the bent portion: 


Around twice their own diameter. Around their own diameter. 
For specimens 1 in. thick 80 deg. For specimens % in. thick 130 deg. 
ce ce 3/4 “cc ‘“c“ go “c“ “é“ 6é 3/16 ce 73 140 6é 
ee ce iy ce “ee I1IO ce “cc ‘7% YZ 6c “ee 180 ce 


No steel which fails to pass the bending test shall under any circum- 
stances be used. 


PROPORTION OF MATERIALS. 


In building construction, the proportions most generally adopted are 1 
part cement to 2 parts sand to 4 parts broken stone or gravel (this being 
customarily indicated by the expression 1:2:4), or I part cement to 2% 
parts sand to 5 parts broken stone or gravel (i.e., 1:244:5). One part is as- 
sumed to be equal to 4 bags of cement, or one barrel, holding 3.8 cubic feet; 
thus proportions 1:2:4 mean one barrel (or 4 bags) Portland cement, 7.6 
cubic feet sand measured loose and 15.2 cubic feet of broken stone or gravel 
measured loose. 

On a small job, where tests cannot be made so economically, it is well to 
be conservative and require proportions 1:2:4. On the other hand, if an en- 
gineéer is constantly present, it is often best not to definitely specify the rela- 
tive amount of sand to stone, but to permit the proportion to vary with the 
material; thus, in laying the concrete if there is an excess of mortar the 
quantity of sand should be slightly reduced and the quantity of stone corre- 
spondingly increased, while if there is insufficient mortar to cover the stone 
and prevent stone pockets, the sand may be increased and the stone decreased. 
The proportion of cement to the sum of the parts of sand and stone may thus 
be kept constant. 


MACHINE MIXING. 


*If the concrete is mixed in a machine mixer a machine shall be selected 
into which the materials, including the water, can be precisely and regularly 
proportioned, and which will produce a concrete of uniform consistency and 
color with the stones and water thoroughly mixed and incorporated with the 
mortar. 


CONSISTENCY. 


For building construction and for other reinforced concrete work it is 
absolutely necessary that the concrete shall be mixed wet enough to flow 
around and thoroughly imbed the steel, but it must be no wetter than is re- 
quired to attain this result. If mixed too dry, air voids will be left around 
the stone, and stone pockets will appear on the face of the concrete after re- 





*See footnote, page 26. 


28 


moving the forms. If, on the other hand, too much water is added, the sur- 
face may have a similar appearance because of the water running away from 
the stone. 


PLACING. 


*Concrete shall be conveyed to place in such a manner that there shall 
be no distinct separation of the different ingredients, or, in cases where such 
separation inadvertently occurs the concrete shall be remixed before placing. 
Each layer in which the concrete is placed shall be of such thickness that it 
can be incorporated with the one previously laid. Concrete shall be used so 
soon after mixing that it can be rammed or puddled in place as a plastic 
homogeneous mass. Any which has set before placing shall be rejected. 
When placing fresh concrete upon an old concrete surface, the latter shall be 
cleaned of all dirt and scum or laitance and thoroughly wet. Noticeable voids 
or stone pockets discovered when the forms are removed shall be immediately 
filled with mortar mixed in the same proportions as the mortar in the con- 
crete. For horizontal joints in thin walls, or in walls to sustain water pres- 
sure, Or in other important locations, a joint of mortar in proportions desig- 
nated by the engineer may be required. 


SURFACES. 


The proper treatment to give a pleasing appearance to exposed surfaces 
is one of the most difficult problems in concrete building construction. The 
surfaces of columns, beams and the undersides of floors can be made suff- 
ciently smooth by careful spading, and by seeing to it that the mortar comes 
to the face and that the forms are tight enough to prevent the mortar running 
out. 

The treatment of the outside surface is determined by the character of 
the structure. A fair surface, suitable for work which is not exposed to view, 
and even for sheds or other buildings where the appearance need not be 
regarded, may be obtained by using a very wet mixture of concrete and by 
careful spading as described above. 

When the character of building and its location is such as to warrant the 
obtaining of an excellent finish, this may be done by either dressing the 
surface after the forms are removed with a pointed hammer, by washing, or 
by rubbing with a block of carborundum or similar substance. These three 
methods, together with others, are described in detail and illustrated in 
chapter on Details of Construction, and the methods adopted in different 
buildings are taken up in the descriptive chapters which follow. 


FORMS. 


*The lumber for the forms and the design of the forms shall be adapted 
to the structure and to the kind of surface required on the concrete. For ex- 





* See footnote page 26. 


29 


posed faces the surface next to the concrete shall be dressed. Forms shall be 
sufficiently tight to prevent loss of cement or mortar. They shall be thor- 
oughly braced or tied together so that the pressure of the concrete or the 
movement of men, machinery or materials shall not throw them out of place. 
Forms shall be left in place until in the judgment of the engineer the concrete 
has attained sufficient strength to resist accidental thrusts and permanent 
strains which may come upon it. Forms shall be thoroughly cleaned before 
being used again 


The time for removal of forms is determined by the weather conditions 
and actual inspection of the concrete. The following approximate rules may 
be followed as a safe guide to the minimum time for the removal of forms.* 


Walls in Mass Work.—One to three days, or until the concrete will bear 
pressure of the thumb without indentation. 


Thin Walls.—In summer, two days; in cold weather, five days. 


Slabs up to Six Feet Span.—In summer, six days; in cold weather, two 
weeks. 


Beams and Girders and Long Span Slabs.—In summer, ten days or two 
weeks; in cold weather, three weeks to one month. If shores are left without 
disturbing them, the time of removal of the sheeting in summer may be re- 
duced to one week. 


Column Forms.—In summer, two days; in cold weather, four days, pro- 
vided girders are shored to prevent appreciable weight reaching columns. 


A very important exception to these rules applies to concrete which has 
been frozen after placing, or has been maintained at a temperature just above 
freezing. In such cases the forms must be left in place until after warm 
weather comes, and then until the concrete has thoroughly dried out and 
hardened. 


FOUNDATIONS. 


In a reinforced concrete building, the floor loads are carried by the slabs 
to the beams and girders, and thence to the columns, which concentrate the 
weight upon small areas of ground. The footing of each column must there- 
fore be spread over a large enough area of ground so as not to overcompress 
the soil and cause appreciable settlement. 


Mr. George B. Francis} suggests the following loading for materials 
which can be clearly defined, at the same time calling attention to the neces- 
sity for varied and ample experience when fixing allowable pressures in any 
particular case: 





__,* From paper on “Forms for Concrete Construction,” by Sanford E. Thompson, before National Asso 
ciation of Cement Users, 1907. 
7 Taylor & Thompson’s “Concrete, Plain and Reinforced,” second edition, page 639, 


30 





Ledge rock, 36 tons per square foot. 
Hard pan, 8 tons per square foot. 
Gravel, 5 tons per square foot. 

Clean sand, 4 tons per square foot. 
Dry clay, 2 tons per square foot. 
Wet clay, 2 tons per square foot. 
Loam, 1 ton per square foot. 


To illustrate the use of these rules: If a column 20 inches square carries 
a load from above of 80 tons, the footing over a soil of dry sand must cover 
an area of §° = 20 square feet; that is, the footing must be about 4 feet 6 
inches square. 

Not only must the area be calculated to distribute the load over a proper 
area of soil, but the thickness of the footing must be computed so as to pre- 
vent the column punching or shearing through it, and a sufficient amount of 
reinforcing steel must be placed in the bottom of the concrete footing to 
prevent its buckling and breaking from the concentrated load of the column. 
The size of the rods is calculated from the bending moment produced by the 
upward pressure of the soil against the projection of the footing, which may 
be assumed to be a beam supported upon a line running through the center 
of the column. If, as is customary, the footing projects in both directions and 
the rods run in both directions, both projections may be taken into account as 
resisting the pressure. 


In certain cases where a very large footing is required, especially when 
the footing rests on piles, stirrups may be needed to resist shear or diagonal 
tension, as in an ordinary beam. 


Proportions of concrete for reinforced footings may be 121455, 1. e., one 
part Portland cement to 2'% parts sand to 5 parts broken stone or gravel, or 
the same proportions may be used as in the building above them. 

Foundations in dry ground which do not require reinforcement and sus- 
tain only direct compression may be laid in proportions of 1:3:6 or 1:3:7. 
If laid under water the concrete should not be leaner than 1:21%4:5, while for 
sea water construction a mixture at least as rich as 1:2:4 is advisable, with 
very careful testing of the cement and aggregates. 

For a building with no basement, foundation walls between the columns 
are unnecessary. The walls may be started just below the surface of the 
ground, and each wall slab will form of itself a beam supported at each end 
by the column foundation. When a basement is included in the design, its 
wall is apt to act as a retaining wall to resist the pressure of earth, and it may 
be necessary to calculate the thickness and reinforcement required to resist 
the earth pressure. Frequently, the bottom of the wall is held by the base- 
ment floor, and the top by the first floor of the building. In this case it may 
be considered as a slab supported at the bottom and top, and the principal 
reinforcing rods should be vertical and placed about one inch from the interior 
face of the wall. If there is no support at the top, the footing may be en- 


31 


larged by careful computation, and a cantilever design made with the princi- 
pal tension rods vertical, but near the exterior face of the wall; or the vertical 
slab may be supported at the ends by columns or buttresses of proper design, 
and the tension rods, computed to resist the earth pressure, run horizontally 
near the interior face. 

For an ordinary cellar wall supported at bottom and top, a thickness of 
8 inches with 3¢-inch vertical rods about one foot apart will be strong enough 
to hold the earth, but it is best to actually compute the thickness and rein- 
forcement for any given case. Even if the principal rods are vertical, occa- 
sional horizontal rods, spaced about 18 inches or 2 feet apart, should be placed 
in the wall to tie it together and prevent contraction cracks. 


BASEMENT FLOOR. 


The earth under a basement floor must be well drained. If necessary, 
drains of tile pipe or of screened gravel or stone may be placed in trenches 
just below the concrete, or the entire level may be covered with cinders or 
stone. If the basement is below tide water or ground water level, it is not 
safe to depend upon the concrete itself being water-tight, and a layer of water 
proofing consisting of four to six layers of tarred paper, mopped on, may be 
spread on the concrete and carried up in continuous sheets on the walls to 
above water level, and the whole surface covered with another layer of con- 
crete. In some cases it may be necessary to make the concrete extra thick, 
cr to add reinforcement, to resist the upward pressure of the water. 


For a basement floor in dry ground a 3-inch or 4-inch thickness of ordi- 
Pary 1:3:5 concrete—that is, concrete composed of 1 part Portland cement to 
3 parts sand to 5 parts broken stone or gravel—may be laid and the surface 
screened to bring it to the required level. As it sets, this concrete should be 
troweled just as the wearing surface of a sidewalk is troweled, but without 
the mortar or granolithic finish which is customarily laid upon a walk. If the 
floor is to have a great deal of wear or trucking, the usual 34-inch or 1-inch 
layer of 1:2 mortar may be laid upon the concrete before it has set, forming a 
part of the total thickness of 4 inches; but usually this is an unwarranted ex- 
pense in a basement, as the plain concrete will give as good service. 

It is well in any case to divide the floor into blocks, say, 8 or 1o feet 
Square, so that any shrinkage cracks will come in the joints. This is readily 


accomplished by laying alternate blocks, and then filling in the intermediate 
ones the next day. 


DESIGN OF FLOOR SYSTEM. 


LOADING.—In designing a reinforced concrete building, the first con- 
sideration is the loading which the various floors must sustain. In addition 
to the specified live or superimposed load the weight of the concrete itself 
must always be allowed for. 


32 


The various conditions met with in warehouse or factory construction 
may necessitate loadings varying from 75 to 1,000 pounds per square foot 
of floor area. As a guide to the selection of floor loads, the following values 
are suggested: 


TICE HOOLS Ser tei cc oie ae mes, ae ate 75 pounds per square foot 
Light running machinery......... 75 to 150 pounds per square foot 
Medium heavy machinery......-....-.. 200 pounds per square foot 
BA Cay Vem ACHING ly tam gree et ecient 250 pounds per square foot 


Storage of parts or finished products, de- 
pending upon actual calculated loads, 
150 to 1,000 pounds per square foot 


When the loads are apt to occur only over a part of the floors, the slabs 
and beams are calculated for the full load, but a reduction of 15 per cent. of 
the live load may be aliowed in figuring the girders. 

In the case of floors supporting machinery whose weight is slight but 
whose motions are great, a proper allowance should be made to take care of 
the resulting vibrations. 


LAYOUT.—The arrangement of the floor beams, girders and columns 
depends upon so many considerations that special study is required in each 
case. 

For heavy loads, say 250 pounds per square foot and over, bays 14 feet 
by 14 feet are generally the cheapest, while for light loads probably 18 feet by 
18 feet is the most economical arrangement of bays. 

In order to secure the most economical arrangement of beams and girders 
it is frequently necessary to make several comparative estimates with different 
spacings of these members. 

The smallest amount of material is required with floor panels of short 
span and frequent floor beams to support them. However, the fact that the 
actual amount of material required for a certain floor construction is less 
than that required in another does not always mean that this floor construc- 
tion is actually the cheapest. If, for example, the beams are closer together 
it must be remembered that the unit labor for the form work is increased, and 
also that of the steel labor. 

The design of a complete floor system with reinforced concrete beams 
girders, slabs and columns, is shown by the isometric view in Fig. 1 (p. 35). 
The columns are spaced 18 by 1g feet on centers and the floor is designed tc 
support a live load of 250 pounds per square foot. 


FLOOR SLABS.—The thickness and reinforcement of the floor slabs 
is determined by the distance between the beams, and by the loading which 
will come upon them. The most usual thicknesses are 314 inches to 5 inches, 
with reinforcement calculated from the bending moment produced by the 
loads. An economical quantity of steel is apt to be from 0.8 per cent. to 1 per 
cent. of the sectional area of the slab above the steel. 


33 


A few rods are usually placed at right angles to the main bearing rods 
of the slab to assist in preventing contraction cracks, and these also add to 
the strength of the slab. 

In a factory or warehouse the most economical floor surface is generally 
a granolithic finish, consisting of a layer of 1:2 mortar about three-quarter 
inch thick, spread upon the surface of the concrete slab before it has begun 
to set, and troweled to a hard finish just like a concrete sidewalk. 

Machines are readily bolted to the concrete by drilling small holes in the 
concrete at the proper points for the standards and grouting the lag screws in 
place, or else bolting them through the slab. 

If for any reason a wood floor is required, stringers may be laid upon the 
top of the concrete and spaces left between them or filled with cinders or 
with cinder concrete. 


BEAMS AND GIRDERS.—As already indicated, the sizes and rein- 
forcement of the beams and girders must be accurately computed by one who 
thoroughly understands the theories involved in reinforced concrete design. 
Even if tables are used the designer must have a knowledge of mechanics and 
of the way in which the stresses act. 

It is a simple matter to determine the amount of steel required in the bot- 
tom of the beam to sustain the pull due to a given loading, but while this is 
an important determination it is by no means the only one. 

The weak points in reinforced concrete structures are not usually due to 
insufficient steel for tension, but more often to an ignorance of other smaller 
details not less important. It is thus absolutely dangerous, and, in fact, crimi- 
nal, for a novice to design or pass upon drawings for a reinforced concrete 
structure. 

In beam and slab construction an effective bond must be provided at the 
junction of the beam and slab. When the principal slab reinforcement is 
parallel to the beam or girder, transverse bars should be placed in the top 
of the slab extending over the beam and well into the slab on each side. 

Where the concrete in the web of beam and the, slab is laid at one 
operation so that there can be no joint between them, the slab may be con- 
sidered as an integral part of the beam, and the beam figured as a T section. 
In this case the effective width of slab considered shall not exceed one-fourth 
of the span length of the beam nor be greater than four times the thickness 
of the slab on either side of the edge of the web. 

The design of reinforced concrete beams and girders involves the follow- 
ing studies: 

(1) The bending moment due to the live and dead loads, this involving 
the selection of the proper formula for the computation. 

(2) Dimensions of beams which will prevent an excessive compression 
of the concrete in the top and which will give the depth and width which is 
otherwise most economical. 


(3) Number and size of rods to sustain tension in the bottom of the 
beam. 


34 







Y 
4, 


i mA 









YAY 
<4 





Pig. 1.—Isometric View of Design of Floor System. (See p. 33) 


(4) Shear or diagonal tension in the concrete. 

(5) Value of bent-up rods to resist shear or diagonal tension. 

(6) Stirrups to supplement the bent-up rods in assisting to resist the 
shear or diagonal tension. 

(7) Steel over the supports to take the tension due to negative bending 
moment. 

(8) Concrete in compression at the bottom of the beam near the sup- 
ports due to negative bending moment. 

(9) Horizontal shear under flange of slab. 

(10) Shear on vertical planes between beams and flanges. 

(11) Distance apart of rods to resist splitting. 

(12) Length of rods to prevent slipping. 

(13) End connections at wall. 

Although it is not the province of this book to go into the mathematical 
treatment of these various points, many of them are as yet so inadequately 
treated in literature on the subject that it will be advisable to touch upon them 
in a general way. 


BENDING MOMENT.—In the design of reinforced concrete beams and 
slabs as much variation may be obtained in the results by the selection of 
the bending moments as in the choosing of working stresses. When the 
beam or slab is designed as continuous over the supports it is absolutely 
necessary that the beam be really continuous both in design and construction; 
that the stresses due to negative bending moment at the support be provided 
for, and that the steel be accurately placed. Under these conditions the 
following formulas are recommended as good practice: 

Let M = bending moment in foot pounds. 

w = load uniformity distributed in pounds per foot of length (both 
live and dead load). 
1— length of member between centers of support in feet. 

To transform the bending moment to inch-pounds, multiply by 12. 

For beams and slabs truly continuous and thoroughly reinforced over 
the supports, 

M = 42 wi’ at center and at support. 

For beams and slabs partially continuous, as end spans, or for continuous 

members of 2 or 3 spans. 


M — \o wl? at center and adjoining support. 
For beams and slabs simply supported at the ends and not continuous. 
M— wh, 

The negative bending moments which exist at the support in continuous 
beams must be provided for by steel-rods carried over the top of the support 
for tension and by a sufficient area of concrete and steel at the bottom of the 
beam near the support to take the compression. If the compression in the 
concrete at the bottom of the beam is excessive the beams must either be 
made deeper next to the support by forming a flat haunch or extra horizontal 


36 


steel must be inserted. The tensile and compressive reinforcement over sup- 
ports must extend sufficiently beyond the support to develop the requisite 
bond strength. 


REINFORCEMENT.—The tensile stress in mild steel must not exceed 
16,000 pounds per square inch. If first-class steel is used and strict adherence 
to the specifications is followed a working stress of 20,000 pounds per square 
inch may be allowed. The compressive stress in reinforcing steel must not 
exceed 16,000 pounds per square inch nor more than 15 times the working 
compressive stress in the concrete. 


SPACING OF BARS.—The lateral spacing of parallel bars should not 
be less than two and one-half diameters, center to center, nor should the 
distance from the side of the beam to the center of the nearest bar be less 
than two diameters. The clear vertical spacing between two layers of bars 
should not be less than 1% inch. 


CONCRETE.—TIf the concrete is made of first-class materials mixed not 
leaner than 1 part cement to 2 parts sand to 4 parts stone, so as to have a 
compressive strength of at least 2,000 pounds per square inch at the age of 
28 days, a value as high as 650 pounds per square inch for the extreme fiber 
compression in beams and slabs may be used with safety, provided the com- 
putation is based on what is termed the straight-line distribution of stress, 
and the ratio of the modulus of elasticity of steel to concrete is taken at 15. 
To guard against the possibility of poor workmanship, building departments 
frequently fix a limit of 500 pounds per square inch. 


WORKING STRESSES IN BEAMS AND SLABS.—The following 
working stresses are for concrete composed of 1 part Portland cement and 
6 parts of aggregates, capable of developing an average compressive strength 
of 2000 pounds per square inch at 28 days: 

a. Modulus of elasticity. The modulus shall be assumed as 1/15 that 
of steel; that is, a ratio of 15 shall be used. 

b. Compression in extreme fiber. The extreme fiber stress in beams and 
slabs calculated for constant modulus of elasticity shall be 650 pounds per 
square inch. Adjacent to the support of continuous beams, stresses 15 per 
cent. higher may be used. 

c. Bearing. For compression on surface of concrete larger than loaded 
area 650 pounds per square inch. 

d. Bond. The bonding stress between concrete and plain reinforcing 
bars shall be 80 pounds per square inch, and between concrete and deformed 
bars from 100 to 150 pounds per square inch, depending upon the character 
of the bar. 


SHEAR AND DIAGONAL TENSION.—The bending of a beam pro: 
duces a tendency of the particles within the beam to pull apart. It is there- 
fore necessary to study the vertical shear, the horizontal shear, and the 


37 


diagonal tension in a beam. When the maximum shearing stresses exceed the 
value allowed in tension for the concrete alone, web reinforcement must be 
provided to assist in carrying the diagonal tension stresses. This web rein- 
forcement may consist of bent bars, or inclined or vertical members attached 
to or looped about the horizontal reinforcement. Where inclined members 
are used the connection to the horizontal reinforcement must be such as to 
insure against slip. Experiments prove that the bending up of the rein- 
forcing bars in different adjoining planes increases the strength of the beam 
in shear to a very considerable extent, and that if the total shearing stress 
for 1:2:4 concrete does not exceed 120 pounds per square inch we are justified 
in assuming that the concrete carries one-third of the shear and the reinforce- 
ment the balance. The following allowable values for the maximum shearing 
stress are recommended by the Joint Committee on Concrete and Reinforced 
Concrete: 


a. For beams with horizontal bars only, 40 pounds per square inch. 


b. For beams in which a part of the horizontal reinforcement is used in 
the form of bent-up bars, arranged with due respect to the shearing stresses, 
(but not figured as taking stress) 60 pounds per square inch. 


c. For beams thoroughly reinforced for shear, a value not exceeding 120 
pounds per square inch, of which, as stated, one-third may be assumed as 
carried by the concrete and the remainder must be provided for by vertical 
or inclined steel. 


COLUMNS. 


The most important of all the members of the building are the columns, 
for if a column fails the entire building is liable to go down. 

Columns of short length, essentially piers, the length of which is not 
more than six times the least lateral dimension, may be built of plain concrete 
with no reinforcement, provided the loading is central. Columns longer than 
this should be reinforced for safety in construction and also to guard against 
the possibility of eccentric loading and the danger of sudden failure. 

The ratio of the unsupported length of a column to its least width should 
be limited to 15. 

The effective area of a column to use in figuring the compression should 
be less than the total area to allow a certain surface covering for fire pro- 
tection. Where the contents of a building are especially inflammable this 
protective covering should be taken to a depth of 1% inches on all surfaces, 
but if the contents are not of a particularly inflammable nature a decrease 
in the total diameter or width of a column of 1 to 2 inches is a fair allowance. 

Columns may be reinforced by means of longitudinal rods, by bands or 
hoops, by bands or hoops together with longitudinal bars, or by structural 
shapes sufficiently rigid to act as columns themselves. Bands or hoops 
increase greatly the “toughness” of a column and its ultimate strength, but 
have little effect upon its behavior within the elastic limit. They do, however, 


38 


tend to make the concrete a safer and more reliable material and should permit 
of a somewhat higher working stress. 

The following recommendations were suggested by the Joint Committee 
for the relative working stresses in the concrete for the several types of 
columns: 


PLAIN COLUMNS.—Plain columns or piers whose length does not 
exceed 12 diameters, 221% per cent. of the compressive strength of 28 days 
or 450 pounds per square inch on 2,0o00-pound concrete. 


REINFORCED COLUMNS.—a. Columns with longitudinal reinforce- 
ment only, the unit stress recommended for plain columns. 


b. Columns with reinforcement of bands or hoops, as hereinafter spec- 
ified, stresses 20 per cent. higher than given for a. 


c. Columns reinforced with not less than 1 per cent. and not more than 
4 per cent. of longitudinal bars and with bands or hoops, stresses 45 per cent. 
higher than given for a. 


d. Columns reinforced with structural steel column units which 
thoroughly encase the concrete core, stresses 45 per cent. higher than given 
for a. 

In all cases, longitudinal steel is assumed to carry its proportion of 
the form of bent-up bars, arranged with due respect to the shearing stresses 
(but not figured as taking stress), 60 pounds per square inch. 

Bars composing longitudinal reinforcement shall be straight, and shall 
have sufficient lateral support to be securely held in place until the concrete 
has set. 

Where bands or hoops are used the total amount of such reinforcement 
shall not be less than 1 per cent. of the volume of the column enclosed. The 
clear spacing of such bands or hoops shall not be greater than one-fourth 
the diameter of the enclosed column. Adequate means must be provided to 
hold bands or hoops in place so as to form a column, the core of which shall 
be straight and well centered. 

Bending stresses due to eccentric loads must be provided for by increasing 
the section until the maximum stress does not exceed the values above 
specified. 

The compressive strength of concrete is approximately proportional 
to the amount of cement which it contains, so that increasing the proportion 
of cement is an effective method of strengthening the column to permit 
smaller section. By using proportions of 1:1:3 a safe working stress of 700 
pounds per square inch may be adopted. If this is done the same mixture 
should be carried up through the floor so that there will be no weak places. 

The following table gives the working loads on concrete columns with 
varying percentage of reinforcement. 


39 


WORKING LOADS ON CONCRETE COLUMNS, REINFORCED WITH LONGITUDINAL 
BARS* 





SSO Allowable Unit Load on Columns, in Lbs., per Sq. In. 
p- Ratio of Moduli, n=10 Ratio of Moduli, n—15 Ratio of Moduli, n~— 20 
(1) (2) | (3) | @) | ©) | ©) | | (8) | (8) | GO) | G1) | (2) |} 3) 

















| fc fc fc fc fc fe= | fe | fc fc fc fc | fc 
450 | 550 | 650 | 750 | 450 | 550 ' 650 | 750 | 450 550! 650 750 








0.01 | 490 599 708 817 513 | 627 741 855 535 654 773 | 892 
0.02 531 649 767 885 576 704 832 960 621 759 897 | 1035 
0.03 | 571 | 698 825 952 | 639 | 781 923 1065 706 863 | 1020 | 1117 
0.04 612 748 884 1020 702 | 858 1014 1170 | 792 | 968 | 1144 | 1320 








Note: —Use column (6) ordinarily for first class 1: 2: 4 concrete. 


*Quoted by permission from Taylor and Thompson’s ‘‘Concrete, Plain and Reinforced,”’ 
Second Edition, page 492. 


WALLS. 


The walls of reinforced concrete factories are sometimes built up with 
the columns, but it is generally considered more economical to erect the skele- 
ton structure and fill in the wall panels, as described in Chapters VI and IX. 

Slots in the columns are made by nailing a strip on the inside of the 
column forms. In this way the panels are mortised into the columns. 

Ordinary concrete walls require light reinforcement to prevent shrinkage 
and give them stiffness while setting. All that is required for, say, a 4-inch 
or 6-inch wall are %4-inch bars spaced from 12 to 24 inches apart, accord- 
ing to the size and importance of the wall.. At window and door openings 
a larger amount of reinforcement is of course necessary, and in these cases 
the amount of steel must be calculated just as though the lintels were rein- 
forced concrete beams. 


ROOFS. 


Reinforced concrete roofs are designed like floors. A roof load commonly 
assumed in temperate climates, to provide for roof covering, snow and wind 
pressure, is 40 pounds per square foot, in addition to the weight of the concrete 
itself. 

It is not safe to assume that the concrete roof of itself will be water-tight 
unless special provision is made in the construction. Although tanks and 
walls can readily be made to hold water, a roof is under extraordinary dis- 
advantageous conditions because of the rays of the sun. Usually, therefore, 
a tar and gravel or other form of roof covering must be provided. 


40 


CONSTRUCTION. 


The details of construction are treated at length for individual buildings 
in the chapters which follow. Chapter XX also takes up many special points 
and treats as well of different methods of reinforcing. 

A reinforced concrete building must have careful inspection while in 
process of erection, the special points to be observed being: 


(1) 


Exact proportioning of materials. 

Placing the concrete so as to prevent separation of ingredients. 
Placing concrete to avoid joints except where called for. 

Exact placing and imbedding of the reinforcement. 

Proper securing of the forms. 

Maintenance of the forms in position until the concrete is sufficiently 


41 


CHAPTER III. 


CONCRETE AGGREGATES.* 


The term “aggregate” includes not only the stone, but also the sand which 
is mixed with cement to form either concrete or mortar; in other words, it is 
the entire inert mineral material. This definition, now generally accepted, 
has replaced the one restricting the term to the coarse aggregate alone. It 
is the object of this chapter to enumerate the general principles which should 
be followed in the selection of sand and stone for mortar and concrete, and 
to describe briefly the method of testing aggregates and determining propor- 
tions which the author has found to give good results in practice. 

At the outset, it may be said that a concrete of fair quality, if rich enough 
in cement, can be made with nearly any kind of mineral aggregate, but there 
is, nevertheless, a wide variation in the results produced. For the fine aggre- 
gate, sand, broken stone, screenings, pulverized slag or the fine material from 
cinders may be used separately or in combination with each other. For the 
coarse aggregate, broken stone, gravel, screened gravel slag, crushed lava, 
shells, broken brick, or mixtures of any of these may be employed. However, 
the very fact of the adaptability of concrete to so wide a range of materials, 
every one of which really consists of a large class varying in size, shape and 
composition, tends to blind one to the economies which often may be effected 
and the improvement in quality which almost always will result by a careful 
selection and proportioning of the aggregates. 

In many cases, especially where the cost of Portland cement is low, it 
may be cheaper to use whatever materials are nearest at hand, and insure the 
quality of the concrete or mortar by making it excessively rich in cement. If 
the structure is small and of little importance this course is properly followed, 
but, on the other hand, if a large amount of concrete is to be laid, and es- 
pecially if the process is to be carried on in a factory, as in concrete block 
manufacture, it pays from the standpoints of both quality and economy to 
use great care in the selection of the aggregates, as well as of the cement, and 
to provide means for maintaining uniformity. 

To illustrate the variation which different aggregates may produce even 
when they are mixed with cement in the same proportions, the author has 
selected a few comparative tests of mortar and concrete. 


*Read by the author before the National Association of Cement Users, June, 1906, 


42 ay ? 


EFFECT OF DIFFERENT AGGREGATES UPON THE STRENGTH 
OF MORTAR AND CONCRETE. 


Tests by Mr. Rene Feret,* of France, with mortar made from different 
natural sands show a surprising variation in strength, which is evidently due 
simply to the fineness of the sand of which the different specimens are com- 
posed. Selecting from his results proportions 1:24 by weight—that is, 1 
part cement to 2!4 parts sand—and converting his results at the age of five 
months from French units to pounds per square inch, the average tensile 
strength of Portland cement mortar made with coarse sand is 421 pounds per 
square inch, with medium sand 368 pounds per square inch, and with fine 
sand 302 pounds per square inch. In the crushing strength, usually the most 
important consideration, the difference is even more marked. In round num- 
bers at the age of five months the mortar of coarse sand gave 5,200 pounds 
per square inch; of the medium sand, 3,400 pounds per square inch, and of 
the fine sand 1,900 pounds per square inch. Note that the different sands 
were not artificially prepared, but were taken from the natural bank and 
correspond to those which every day are being used for concrete and mortar. 

The effect of different mixtures of the same kind of material is shown by 
tests made by the author in 1905.+ By varying the sizes of the particles of 
the aggregates, but using in all cases stone from the same ledge and the same 
proportion of cement to total aggregate by weight, namely, 1:9 (or approxi- 
mately 1:3:6), it was found possible to make specimens the resulting 
strengths of some of which were two and a half times the strength of others. 

The effect of the hardness or strength of the stone used for the coarse 
aggregate is shown in tests of George W. Rafter,t which, for proportions 
about 1:261%, gave 50 per cent. greater compressive strength of concrete where 
the coarse aggregate was a hard sandstone than with similar proportions 
where a shale was substituted. In some of his tests the harder stone gave a 
concrete even double the strength of the concrete with softer stone. 


GENERAL PRINCIPLES FOR SELECTING STONE. 


The quality of concrete is affected by the hardness of the stone, the shape 
of the particles, the maximum size of the particles and the relative sizes of 
the particles. 

If broken stone is used, and there is an opportunity for choice, the best 
is that which is hard; with cubical fracture; with particles whose maximum 
size is as large as can be handled in the work; with the particles smaller than, 
say, 1% inch, screened out to be used as sand; and with the sizes of the re- 
maining coarse stone varying from small to large, the coarsest predominat- 
ing. 

If gravel is used it must be clean. The maximum size of particles should 
be as large as can be handled in the work; grains below, say, 1% inch, should 

“Taylor & Thompson’s “Concrete, Plain and Reinforced,” page 136. 


{Proceedings American Society of Civil Engineers, Vol. LIX, 1907, 
tSecond Report on Genesee River Storage Project, 1894. 


43 


be screened out to be used as sand, and the size of the stone should vary, 
with the coarsest predominating. 

As already stated, the size of the coarsest particles of stone should be as 
large as can be handled in the work. This is because the strength of the con- 
crete is thereby increased and a leaner mixture can be used than with small 
stone. In mass concrete the stones if too large are liable to separate from the 
mortar unless placed by hand or derrick, as in rubble concrete, and a practical 
maximum size is 21% or 3 inches. In thin walls, floors and other reinforced 
construction, a 1-inch maximum size is generally as large as can be easily 
worked between the steel. In some cases where the walls are very thin, say 
3 or 4 inches, a 34-inch maximum size is more convenient to handle. 

It is a little more trouble but almost always best to screen out the sand 
from gravel or the fine material from crusher stone, and then remix it in the 
proportions required by the specifications, for otherwise the proportions will 
vary at different points, and one must use and pay for an excess of cement 
to balance the lack of uniformity. 

If the gravel is used, it is absolutely essential that it shall be clean, be- 
cause if clay or loam adheres to the particles, the adhesion of the cement will 
be destroyed or weakened. Tests of the Boston Transit Commission* give 
an average unit transverse strength of 605 pounds per square inch for con- 
crete made with clean gravel as against 446 pounds per square inch when 
made with dirty gravel. 


COMPARATIVE VALUES OF DIFFERENT STONE. 


Different stones of the same class vary so widely in texture and strength 
that it is impossible to give their exact comparative values for concrete. A 
comparison by the author of a large number of tests of concrete made with 
different kinds of stone indicates that the value of a broken stone for concrete 
is largely governed by the actual strength of the stone itself, the hardest stone 
producing the strongest concrete. This forms a valuable guide for comparing 
different stones. Comparative tests indicate that different stones in order 
of their value for concrete are approximately as follows: (1) Trap, (2) gran- 
ite, (3) gravel, (4) marble, (5) limestone, (6) slag, (7) sandstone, (8) slate, 
(9) shale, (10) cinders. Although as stated above, the wide difference in the 
quality of the stone of any class makes accurate comparisons impossible— 
and this difficulty is increased by the fact that the proportions and age of the 
specimens affect their relative value—an approximate estimate drawn from 
actual tests gives the value for concrete of good quality sandstone as not 
more than three-fourths the value of trap, and the value of slate as less than 
half that of trap. Good cinders nearly equal slate and shale in the strength 
of concrete made with them. 

The hardness of the stone grows in importance with the age of the con- 
crete. Thus gravel concrete, because of the rounded surfaces, at the age of 
one month may be weaker than a concrete made with comparatively soft 


*Seventh Repert of Boston Transit Commission, 1901, page 39. 


44 


broken stone; but at the age of one year it may surpass in strength the broken 
stone concrete, because as the cement becomes hard, there is greater tendency 
for the stones themselves to shear through, and the hardness of the gravel 
stones thus comes into play. Gravel makes a dense mixture, and if much 
cheaper than broken stone, can usually be substituted for it. 

A flat grained material packs less closely and generally is inferior to 
stone of cubical fracture. 


GENERAL PRINCIPLES FOR SELECTING SAND. 


The only characteristics of sand which need be considered are the coarse- 
ness of its grains and its cleanness. These qualities affect the density of the 
mortar produced, and therefore the test of the volume of mortar, or “yield” 
determines which of two or more sands is best graded. The “yield” or 
“volumetric” test is considered by the author of greater value for quick re- 
sults than all others put together. The methods of employing it are described 
farther along in the paper. 

The best sand is that which produces the smallest volume of plastic 
mortar when mixed with cement in the required proportions by weight. 

A high weight of sand and a corresponding low percentage of voids are 
indications of coarseness and good grading of particles; but because of the 
impossibility of establishing uniformity in weighing or measuring, they are 
merely general guides which cannot under any conditions be taken as positive 
indications of true relative values. The various characteristics of sands are 
separately considered in the following paragraphs: 

WEIGHT OF SAND.—A heavy sand is generally denser, and there- 
fore better than a light sand. However, this is not a positive sign of worth, 
because the difference in moisture may affect the weight by 20 per cent., and 
when weighed dry the results are not comparable for mortars, since fine sand 
takes more water than coarse. 

As an illustration of the variation in weight of natural sands having 
different moisture, the author found that the weight per cubic foot of Cowe 
Bay sand, which dry averaged 103 pounds, when placed out of doors and after 
a rain shoveled into a measure and weighed in exactly the same way 
(although it was allowed to drain for two days) averaged 83 pounds. 

VOIDS IN SAND.—The voids, like the weight, are so variable in the 
same sand, because of different percentages of moisture and different methods 
of handling, that their determination is of but slight value. In the Cowe Bay 
sand just mentioned, the voids were 38 per cent. in the sand, dry, and 52 per 
cent. in the same sand, moist. 

Because of such discrepancies, the author prefers to mix the sand with 
the cement and water, and determine the voids in the fresh mortar, as de- 
scribed later. This gives a true comparison of different sands, since with the 
same percentage of cement, the mortar having the lowest air plus water voids 
is the strongest. 


45 


COARSENESS OF SAND,.—A coarse sand produces the densest, and, 
therefore, the strongest mortar or concrete. A sufficient quantity of fine 
grains is valuable to grade down and reduce the size of the voids, but in 
ordinary natural material, either sand or screenings, there will be found suffi- 
cient fine material for ordinary’ proportions, such as 1:1, 1:2, or 1:24%4. For 
leaner proportions, such as 1:4 or: 1:5, and sometimes 1:3, an addition of fine 
particles will be found advantageous to assist the cement in filling the voids. 
A dirty sand, that is, one containing fine clay or other mineral matter, up to 
say, Io per cent., is actually found by tests to be better than a clean sand for 
lean mortars. 

For water-tight work it is probable that a larger proportion of very fine 
grains may be employed than for the best results in strength. This is a 
question, however, which has not yet been thoroughly investigated. 

Feret’s rule for sand to produce the densest mortar is to proportion the 
coarse grains as double the fine, including the cement, with no grains of in- 
termediate size. There is difficulty in an exact practical application of this 
rule, but it indicates the trend to be followed in seeking maximum density 
and strength. 


CLEANNESS OF SAND.*—An excess of fine material or dirt, as has 
just been noted, weakens a mortar which is rich in cement. It may also 
seriously retard its setting. The author’s attention was recently called to a 
concrete lining, one portion of which failed to set hard for several weeks, 
although the same cement was used as on adjacent portions of the work. 
The difficulty proved to be due entirely to the fact that the contractor sub- 
stituted, in this place, a very fine sand, the regular material happening to run 

low. 


SHARPNESS OF SAND.—Notice that the quality of sharpness has not 
been mentioned among the essential characteristics of sand. This omission 
was intentional. The majority of specifications still call for “sharp” sand, 
and yet the writer has never known a sand to be rejected simply because of 
its lack of sharpness. As a matter of fact, if two sands have the same sized 
grains, and contain an equal amount of dust, the one with rounded grains 
is apt to give a denser and stronger mortar than the sharp grained sand. A 
sand with a sharp “feel” is preferable to another, not to any extent because 
of its sharpness, but because the grittiness indicates a silicious sand which is 
apt to have no excess of fine material. 


SAND VS. BROKEN STONE SCREENINGS.—Many comparative 
tests of sand and screenings have been made with contrary results. While 
frequently crusher screenings produce stronger mortar than ordinary sand, 
the author in an extensive series of tests has found the reverse to be true. 
This disagreement is probably due to the grading of the particles, although 
in certain cases the screenings may add to the strength because of hydraul- 
icity of the dust when mixed with cement. 





*The danger of vegetable impurities and the necessity for tensile tests referred to on page 25. 


46 


TESTING SAND. 


In the previous paragraphs are shown the defects in the more common 
methods of examining sand. 

Tests made by the author in 1903 proved the value of the principles of 
the density of mortars laid down by Feret, and in the winter of that year 
similar plans for testing aggregates were introduced by Mr. William B. Fuller 
and the author at Jerome Park Reservoir, New York City. The object of the 
test is to determine which of two or more sands will produce the denser, and 
therefore the stronger, mortar in any given proportions. 


The different results in strength which Mr. Feret found with coarse, 
medium and fine sand respectively have already been given, these relative 
strengths in compression being respectively 5,200, 3,400 and 1,g00 pounds, 
with proportions 1:214 by weight in each case. An examination of the tests 
shows that the strongest mortar was also densest; that is, the smallest 
volume or yield of mortar was produced with a given weight of aggregate. 

The mortar of medium sand occupied a volume 714 per cent. in excess of 
the volume of the mortar with coarse sand; and the mortar of fine sand, a 
volume 17 per cent. in excess of the mortar with coarse sand. 

Following these principles, two sands may be compared and the better 
one selected by determining which produces the smallest volume of mortar 
with the given proportions by weight. Using the method described below, 
the author has been able to increase the strength of a mortar about 4o per 
cent. by merely changing the sizes of grains of the aggregate. 


The method of making the test is as follows: If the proportions of the 
cement to sand are by volume, they must be reduced to weight proportions; 
for example, if a sand weighs 83 pounds per cubic foot moist, and the moisture 
found by drying a small sample of it at 212° Fahr. is 4 per cent., which cor- 
responds to about 3 pounds in the cubic foot, the weight of dry sand in the 
cubic foot will be 83 — 3=— 80. If the proportions by volume are 1:3, that is, 
one cubic foot dry cement to 3 cubic feet of moist sand, and if we assume the 
weight of the cement as 100 pounds per cubic foot, the proportions by weight 
will be 100 pounds cement to 3x80==240 pounds sand, which correspond to 
proportions 1:2.4 by weight. 

A convenient measure for the mortar is a glass graduate, about 114 inches 
in diameter, graduated to 250 cubic centimeters. A convenient weight of 
cement plus sand, for a test, is 350 grams. For weighing, the author employs 
Harvard Trip scales, which weigh with fair accuracy to one-tenth of a gram. 
The sand is dried and mixed with cement, in the calculated proportions, in a 
shallow pan about ro inches in diameter and 1 inch deep. The mixing is con- 
veniently done with a 4-inch pointing trowel. The dry mixed material is 
formed into a circle, as in mixing cement for briquets, and sufficient water 
added to make a mortar of plastic consistency, similar to that used in laying 
brick masonry. After mixing five minutes, the mortar is introduced about 
20 c.c. at a time into the graduate, and to expel any air bubbles, is lightly 


47 


tamped with a round stick with a flat end. The mortar is allowed to settle 
in the graduate for one or two hours until the level becomes constant, when 
the surplus water is poured off, and the volume of the mortar in cubic centi- 
meters is read. For greater exactness, a correction may be introduced for 
mortar remaining on pan and trowel. The other sands, which are to be com- 
pared with this one, are then mixed with cement in the same proportions by 
dry weight, and sufficient water added to give the same consistency. The 
percentage of water required will vary with the different aggregates, the 
finer sand requiring the more water. After testing all the mortars, the sand 
which produces the strongest mortar is immediately located as that in the 
mortar of lowest volume. By systematic trials, the best mixture of two or 
more sands may also be found. 

In some cases a correction must be introduced for the specific gravity of 
the sand; for example, ordinary bank sand has an average specific gravity 
of 2.65, but if this is to be compared with broken stone screenings having a 
specific gravity of, say, 2.80, the proportions of the two must be made slightly 
different. For these particular specific gravities, proportions 1:3, by weight, 
with sand, correspond in absolute volume to proportions 1:3.2, by weight, 
of the screenings. 

In making these tests, it is also important to notice the character of the 
mortar as it is being mixed. It should work smooth under the trowel and be 
practically free from air bubbles. 


CALCULATING RELATIVE STRENGTHS OF MORTARS. 


From the results of the tests described, it is possible to very closely esti- 
mate the relative strength of different mortars made with the same cement. 
A formula is given by Mr. Feret* for calculating the strength from the abso- 
lute volumes of the ingredients of the mortar, but, wishing to avoid the calcula- 
tion of the absolute volumes and obtain the result directly from the weights 
of the materials and the volume of the mortar made from them, the writer has 
found it possible to evolve from Feret’s formula one which makes use only of 
the data from the tests in the graduates above described. 


The formula is as follows: 


Let 
P = compressive strength of mortar in pounds per square inch. 
K°==a constant. 
Q = measured volume or quantity of mortar in cubic centimeters. 
C —weight of cement used in grams. 
S = weight of sand used in grams. 
Gc= specific gravity of cement. 
Gs= specific gravity of sand. 


Then G.\2 Cc 2 
ee ee-s) 


*Taylor & Thompson’s ‘‘Concrete, Plain and Reinforced,’’ second edition, page 140. 


48 


This formula may be readily altered to apply to the English system of 
weights and measures. 

The value of K varies with different cements and different ages of the 
same mortar, hence, it is simplest to disregard the actual strength, and con- 
sider the relative strengths of any two or more mortars as in direct proportion 
to the values of the square of the quantities in brackets. 

If the aggregates to be compared have similar specific gravity, as in the 
case with different natural sands, the relative strengths of the mortars will be 


in proportion to the values of 
CG 2 
(a. es) 


To illustrate the practical value of the formula, aside from the theory, it 
may be of interest to refer to a recent series of comparative tests made in the 
author’s laboratory. A mixture of sand and cement in proportions 70 grams 
cement to 276 grams sand produced in the graduate a volume of mortar of 
178 c.c. After making a number of trial tests, using in every case the same 
proportions by weight, a new mixture of sizes of the same aggregate was ob- 
tained, whose volume when mixed with the cement and water was 165 c.c. 
The specific gravity of the sand, which in this instance was crushed rock, 
in both cases was 2.88. Substituting these values in the formula, we find the 
ratio of the two tests to be 1 to 1.40, that is, the mortar having the smallest 
volume ought to be 1.40 times (or 4o per cent.) stronger than the other. 
Actual tests of the two mortars,—afterwards made in similar proportions 
into long prisms,—gave at the end of 14 days an average of 832 pounds per 
square inch for one and 1,153 pounds per square inch for the other, thus 
showing an actual excess of strength of 39 per cent., which is substantially 
identical with the estimated increase. 


TESTING CONCRETE AGGREGATES. 


For concrete in any given proportions, the best sizes of stone and of sand 
may be determined by similar methods to those described for testing sand 
mortars, although larger quantities of materials must be used and the measure 
must be strong to withstand the light ramming which is necessary. A short 
length of cast iron pipe, closed at one end, may be used for this. 

The aggregates, which mixed with cement in the required proportions 
produce the smallest volume of concrete, are usually the best, although, as 
already indicated, the shape of the particles and their hardness must also be 
taken into consideration. 


PROPORTIONING CONCRETE. 


A general principle of practical use in determining the relative propor- 
tions of two or more aggregates in a concrete is that, the weight of material 
and the percentage of cement remaining the same, the mixture producing the 
smallest volume of concrete is the best. 


49 


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50 


CHAPTER IV. 


PLANT OF CARTER’S INK COMPANY. 


The new plant of the Carter’s Ink Company, Cambridge, Mass., located 
on a lot facing the Charles River, is an illustration of the architectural possi- 
bilities of reinforced concrete in factory construction. A large majority of 
concrete factories have been built with no regard whatever to appearance, 
when with a comparatively small increase in cost it is possible to produce an 
artistic structure. In the present case the location of the plant on the future 
Charles River parkway demanded a careful architectural treatment. 

Reinforced concrete was chosen on account of its adaptability to archi- 
tectural design, its economy for the loads required, its fireproof qualities, rapid- 
ity of erection, and freedom from vibration. 

The plant includes a main building for the manufacture and storage of 
the company’s products, an external toilet room and stairway tower, a power 
house, and a glass storage building. 

The main building (shown in Fig. 2) is an L-shaped structure, four 
stories high, with a maximum length of 186 feet, a height of 78 feet and an 
average width of 64 feet. The one-story power house is also of reinforced 
concrete, 69 feet long and 41 feet wide. The glass storage building, 83 feet 
long and 61 feet wide, is a one-story frame structure with exterior walls of 
plaster on wire-lath and concrete floor. 

Densmore & LeClear, of Boston, were the architects and the Aberthaw 
Construction Co., of Boston, the contractors. 


EXTERIOR DESIGN. 


In order to gain an architectural effect in keeping with the prominent 
location of the building, the front and sides were designed with recessed win- 
dow arches, and variations in window grouping, and trimmed with cast orna- 
mental work and a cornice of quite elaborate design. Winchester gravel was 
used in the concrete panels and piers, the face being hand picked with smooth 
draft lines on the various panels to give the proper contrast between the com- 
ponent parts of the front and sides. 


REINFORCED CONCRETE DESIGN. 


The company’s work imposed heavy floor loads and somewhat longer 
spans than usual in mill construction. The total dead and live loads used in 


51 


the design were: Basement, 200 pounds per square foot; first floor, storage 
division, 485 pounds; offices, 150 pounds; lavatory and locker rooms, 125 
pounds; second floor, 240 pounds; third and fourth floors, 355 pounds; fourth 
mezzanine, 320 pounds. 

In general, Johnson corrugated bar girder frames were used for reinforce- 
ment, the tensile stress allowed being 16,000 pounds per square inch. 

The concrete for the slabs and girders was mixed in the proportions of 
1 part Atlas Portland Cement to 2 parts sand to 4 parts broken stone passing 
a 1-inch mesh, while the column mixture was 1:114:3. In the beams and slabs 
a fibre stress of 600 pounds per square inch was allowed and the columns were 
figured on the basis of 600 pounds per square inch in compression. 

All curtain walls, and also the basement retaining wall, were of 1:214:5 
mixture with an addition of 1 part of hydrated lime to 10 parts of cement, to 
make it more water-tight. 


(IES Contrele 








wae soda / & 4- 
ee di Bars. ae 




















Dela// of yL2tca/ Bearn 
Fig. 3.—Details of Typical Girder and Main Column Footings. (See pp. 52 and 54) 


A typical first-floor girder is shown in detail in Fig. 3 (p. 52). These 
girders have 20-foot spans and are spaced to feet 6 inches on centers. They 
are 20 inches wide and 32 inches deep, reinforced with five 14-inch and four 
1¥g-inch bars. Four of the 114-inch bars are bent up at the quarter points and 
carried over the support. Each girder has twenty-four 14-inch V stirrups 
spaced as shown. 

The floor slabs are 71% inches thick, reinforced with 54-inch bars spaced 
53% inches apart. 

The photograph in Fig. 4 of the interior of the basement shows the col- 
umns and floor system. 


52 





Fig. 5.—View of Carter’s Ink Factory During Construction. (See p. 
53 


The columns throughout are reinforced with four 1-inch and two 34-inch 
bars, with 14-inch hoops 12 inches on centers. 

Fig. 5 shows the form work and reinforcement in place for the second- 
floor construction. 


FOUNDATIONS. 


The foundation soil is filled land on clay, silt and streaks of sand, and 
about 200 spruce piles averaging 20 feet in length and 10 inches in diameter 
at the top were required to carry the buildings. Each pile was figured to carry 
ten tons. 

The footings for the main columns, of which a typical design is shown in 
Fig. 3, are of the spread type, each resting upon 24 piles placed 24 inches 
apart on centers and in rows, 30 inches apart. In general the foundations are 
of the cut pyramid form and heavily reinforced. 

The basement curtain walls are carried from footing to footing, being 
reinforced as girders with horizontal bars to carry their own load and also 
with vertical bars to act as retaining walls. 


COST. 


The total cost of the plant was about $160,000. The forms for the col- 
umns cost 18 cents per square foot of surface and for the floors 11 cents per 
square foot of superficial surface. The concrete for the beams and floor slabs 
cost $6.20 per cubic yard and for the columns $7.25 per cubic yard, while the 
reinforcing steel cost $41 per ton in place. 


54 


CHAPTER V. 


KETTERLINUS BUILDING. 


The plant of the Ketterlinus Lithographic Manufacturing Company is 
located in Philadelphia at the northwest corner of Fourth and Arch streets, 
and the reinforced concrete portion of the structure built in 1906 represents 
a type of building adapted to city manufacturing establishments limited to a 
comparatively small ground area. The building illustrated on a following 
page as Fig. 7 is eight stories high besides the basement, and its dimensions 
are 80 by 67 feet. The architects and engineers were Ballinger & Perrot, of 
Philadelphia, and they also supervised the erection, which was done by day 
labor with no general contractor. 

This new building adjoins and forms a part of the old plant of the Ketter- 
linus Company, which is of steel frame construction, fireproofed with terra 
cotta. 

In both buildings heavy machinery is now running, and many large print- 
ing presses are at work on the third, fourth and fifth floors. Because of the 
proximity of the old and new types of construction the advantages of the re- 
inforced concrete from the point of view of the manufacturer are particularly 
evident. In the building of steel and terra cotta construction the vibration 
from the machinery is noticeable as soon as one enters, while, on the other 
hand, in the new structure the concrete, because of its greater mass and inertia, 
absorbs the vibrations, and it is difficult to appreciate the speed and power 
of the machines. As a result, too, of this reduction in the vibration the noise 
of the machinery is effectually deadened. 

The building is designed for a working load of 400 pounds per square 
foot. The concrete for practically the whole of the work was proportioned 
1:214:5, equivalent by actual measurement to one barrel (4 bags) Atlas Port- 
land cement to 91% cubic feet of sand to 19 cubic feet broken stone, the basis 
of proportioning is in a barrel of 3.8 cubic feet. The sand was well graded 
coarse material, frequently termed in the region of Philadelphia “Jersey grav- 
el”; the stone was trap rock broken to a size at which all the particles would 
pass a one-inch ring excepting the stone in the concrete immediately sur- 
rounding the steel, which was of a size to pass through a half-inch ring. 

To harmonize with the old adjoining building of which it forms a part, 
the exterior walls are faced with brick with terra cotta trimmings. 


DESIGN. 


Several features in the design of the Ketterlinus building are of unusual 
interest. The columns below the fifth floor, instead of the usual solid con- 


55 


crete construction with four or more round rods for reinforcement, are es- 
sentially steel columns surrounded by concrete. The beams and girders are 
reinforced with the unit frame system in which the steel is all put together 
in the shop and brought to the job ready to place in the form. The sawtooth 
roof is also a novel feature for reinforced concrete. 

The columns are spaced 13 feet 6 inches apart in one direction and 19 
feet 2 inches in the other. The girders follow the shorter span, and the bays 
are divided into three panels by the cross beams, as shown in Fig. 6. The 
vertical section, Fig. 8, also illustrates the arrangement of the columns and 
beams, the window lintels and the sections of brick wall below the windows. 


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Fig. 6—Typical Floor and Roof Plans of the Ketterlinus Building. 
56 





Fig. 7.—The Ketterlinus Building. (See p. 55) 


37 


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Fig. 8.—Cross-Section of Ketterlinus Building. (See p. 56) 


cae eet 58 


COLUMNS. 


One of the problems in concrete building construction where the loads 
are heavy or the building is several stories high is to build the columns small 
enough to satisfy the requirements of the occupants and owners without over- 
loading the concrete. Its solution is especially difficult in a city building 
where the land area is so valuable that every square inch of floor space is at a 













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Fig. 9.—Details of Columns and ‘Girders. (See p. 60) aa 








59 


premium, and where there must be more stories than are economical under 
other conditions. Moreover, the building laws of many cities require more 
conservative loading than might be warranted if it were certain that the con- 
ditions of construction were in all cases the best. 

In a number of recent instances the difficulty has been met by the use of 
composite columns, a combination of concrete and structural steel, and this 
is the plan followed by the designers of the Ketterlinus building. Full details 
of the column construction are presented in Fig. 9. 

The interior columns in the building up to the fifth floor are 23 inches in 
diameter. In the basement and the four lower stories, the core of the column 
is formed of steel plates and angle irons riveted together in the form of a 
cross. Around this cross ¥g inch wire ties were placed every 12 inches and 
looped around four vertical round rods which increased the reinforcement. 
In the basement, for example, the centre steel is made up of a plate 18 inches 
wide and 5 inch thick with two plates of similar thickness but 8 inches wide 
at right angles to it, and four angle irons 6 by 6 by % inch all riveted together. 
The four round rods, which complete the so-called “Star” reinforcement are 
1% inch diameter. 

The columns in the three stories nearest the top are designed to carry the 
full dead and live loads of floors and roof. In each lower story the columns 
are designed to carry the full dead load and a smaller proportion of the full 
live load than can be carried by the floor construction, this live load factor 
being reduced proportionately to the number of floors carried; for example, 
the basement columns were calculated on a basis of carrying on the steel cores 
alone three-fourths the live load plus the full dead load with a factor of safety 
of 4. 

The steel is designed to bear the computed load without exceeding a 
maximum compression of 16,000 pounds per square inch. The compressive 
strength of the concrete in these columns is not considered, though almost 
sufficient to carry the dead load. 

The weight of the girders is borne in part by brackets of steel riveted to 
the angle irons and partly by the concrete knees or enlargements of the 
columns which run out obliquely from the columns and which are reinforced 
on each side by two 14-inch rods. 

Above the fourth story the columns are of the same diameter but with 
the more ordinary reinforcement of four round rods. 


COLUMN FOOTINGS. 


To transmit the compressive load from the steel in the columns to the soil, 
a special design of footing was prepared. A large base was necessary to pre- 
vent too great loading of the soil beneath the building, and in order that the 
pressure from the column might not break or crush the concrete over this 
large area a grillage of steel I-beams was placed under each column (See Fig. 
g), and the concrete below these I-beams further strengthened against break- 


60 


age and shear by 1-inch horizontal round rods placed 6 inches apart, and 1g 
by 1-inch stirrups. 


FLOOR SYSTEM. 


Each girder was designed as an independent beam supported at the ends 
by the enlargement of the columns and the steel brackets. The area of the 
reinforcing steel was calculated in the usual way, but instead of placing each 
rod separately in the form, girder frames were made from quadruple or twin 
webbed bars, which were cut, bent to shape and stirrups fastened thereto in 
the shop. The girder frame reinforcement was brought to the building in the 
form of a truss, and the work of placing consisted simply of setting this truss 
in the form upon cast steel sockets, each having a 34-inch threaded stud pro- 
jecting upward through the frame. A nut screwed down on this stud over 
the frame holds it rigidly in position. Every rod and every member could not 
help but be in exactly the right location in the beam. This girder frame and 
socket were the invention of Emile G. Perrot, one of the firm of architects 
who designed the building, the object being to insure the exact amount and 
arrangement of tension and shear members in the exact location as designed, 
and to afford opportunity for inspection of the steel in position before the 
pouring of the concrete. 

In the various plans the letter “Q” is entered as a part of the description 
of the reinforcement. This stands for the word “Quadruple” and indicates a 
group of four rods held at intervals by special sockets. 

The rods are rolled in sets of four connected by a web, and this web is 
sheared and bent down in 2-inch lengths at intervals of 3 inches to give 
greater grip in the concrete. These 2-inch lengths are bent back over stir- 
rups, where they occur, to clinch them in position on the frame. The outside 
bars are also cut loose at each end and bent upwards to reinforce the top of 
the beam near the supports. The sockets (Fig. 9) are shaped so that they 
support the rods 14% inches above the bottom of the beam or girder, and are 
held in place by a 34-inch bolt passing up through the bottom of the wood 
mold. These threaded sockets afterwards are used for securing shafting, 
hangers or other fixtures. 

In the various dimensions of beams on the plan the width and depth is 
given first, followed by “1 Q” or “2 Q” (the latter meaning 8 rods), then the 
diameter of rod, and finally the thickness of the web forming a part of the rods. 
Thus 10’x18"-2074"x14" means that the beam is 10 inches wide by 18 inches 
deep, reinforced with two groups of four rods 7% inch diameter, connected 
longitudinally by webs % inch thick. The depth of the beams and girders is 
given from the under side of the slab instead of from the top of the slab, the 
more usual form. The area of cross-section of each of such “Q” bars is 
about 3 square inches. 

The slabs are of usual construction, being 4 inches thick and reinforced 
for the net span of 3 feet 10 inches with 3-inch No. 10 expanded metal, this 
mesh having been substituted instead of 34-inch rods spaced 6 inches apart 


61 


The sleepers are placed on the concrete slab and cinder 


The wearing surface is a 1%4-inch maple wood floor on 2 by 4-inch sleep- 
concrete in proportions 1:3:7 filled in between them. 


and occasional 44-inch rods running in the other direction, as originally shown 
on the drawings, at an increase of about one per cent. of the cost of the build- 


ing. 
ers 16 inches apart. 


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62 


Fig. 10.—Stairs in Ketterlinus Building. 


STAIRS. 


The stairs are carried up in brick towers, as required at date of construc- 
tion by the Philadelphia building laws. The details of the design and rein- 
forcement are illustrated in Fig. ro. 

The treads are formed by 1-inch thickness of 1 to 1 mortar or grano- 
lithic finish, and the reinforcement consists of 54-inch rods placed 6 inches 
apart. 

WALLS. 


The walls are essentially reinforced concrete columns, veneered on the 
outside with 4 inches of brickwork and separating the windows. The window 
lintels are of concrete faced with terra cotta to match the red sandstone of the 
older building adjoining and anchored to the concrete. The lintels form re- 
inforced concrete beams and support a brick wall 13 inches thick, which is run 
up to the bottom of the terra cotta window sills. 

The method of connecting the brick with the concrete of the columns 
is shown in Fig. 11, copper wall ties 1/16 by 34 by 7 inches being set in the 
concrete at intervals, and, after the removal of the forms, bent out and laid 
into the joint of the face brick, which is separated from the concrete by a 
34-inch mortar joint for purposes of alignment. 





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Fig. 11.—Brick Wall Ties. 
ROOF. 


The general design of the saw-toothed roof appears on the full cross- 
section, Fig. 12 (p. 64). In Fig. 12 the details are illustrated. Inclined gird- 
ers extend across the building, and above these project the saw teeth, which 
rest upon concrete beams running into the girders. Saw-tooth construction 
in reinforced concrete is, of course, expensive, because of the irregularities of 
the forms, but with the aid of the unit reinforcing system, which accurately 
locates the steel, the design is satisfactorily worked out. 

As in the other plans, the letter Q indicates a quadruple bar whose web 
thickness is designated by the final fraction in the dimensions. In the roof, 
instead of the four bars being on one plane and rolled all together with a 
single web, they are arranged in pairs with a web connecting the two bars 
of each pair. 


63 


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Fig. 12.—Cross-Section Detail of Saw-Tooth Roof. (See p. 63) 
CONSTRUCTION. 


The concrete was mixed in the basement by a Smith machine, dumped 
from the mixer into wheelbarrows and raised on a platform elevator located 
in the stair tower to the floor in process of construction, when it was wheeled 
in the same barrows and dumped directly into the columns or floor. 

A boom derrick was employed to handle the steel columns, lumber and 
brick. This derrick was also used for demolishing and excavating before the 
concrete was started. 

A photograph of one of the floors ready for the concrete is shown in Fig. 
13. The wood forms for the beams, girders and slabs are in place, and the 
steel of the columns is set and temporarily braced with plank. In different 
places on the floor the unit girder frames are seen, some of them in place 
in the mold and some lying on the floor ready to be carried and lowered to 
position. 

The progress per story varied from eleven days to three weeks. The 
forms were left in place two weeks or more and were used three times, the 
approximate salvage on the lumber for the next job being 25 per cent. 

The interior of the building is photographed in Fig. 14 (p. 66), and shows 
one of the 20-ton lithographic presses. 


COST. 


The concrete portion of the building cost $27,000. This sum included the 
form work and steel reinforcement, except the column cores and grillage 
beams, which cost $5,500 additional. The total cost of the structure, includ- 
ing the inside finish, amounted to nearly $90,000. 


64 


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66 


The unit girder construction is somewhat more expensive than the ordi- 
nary system of bending and placing separate rods, but the result is a sure 
location for every member with no danger of a road being left out or placed so 
high as to lose a large part of its efficiency. In this particular building the 
cost of the unit girder reinforcement was 5 4 cents per pound after bending 


ready to place. 
INSURANCE. 


It is of interest to observe that the building is insured by the Associated 
Factory Mutual Insurance Companies, and at the time of completion was the 
only building in the congested portion of Philadelphia which was insured 
by them. 

As a protection against fires in neighboring structures, the building is 
fitted with wire glass windows with metal frames, except in the first story, 
which has plate glass windows with metal frames. Openings in the division 
wall between the old and new parts of the plant are closed with automatic 
fire doors on both sides of the fire wall. Furthermore, the building is 
equipped with automatic sprinklers supplied by a tank located 20 feet above 
the roof. The sprinklers are also connected with a 750-gallon Underwriters’ 
fire pump supplied by two independent 6-inch connections from the distribu- 
tion system of the city waterworks, and the tank above the roof and stand- 
pipes in the building are also supplied from this pump. In addition to this 
private fire system, a standpipe extending to a nozzle monitor on the roof is 
also provided, which is connected with the Underwriters’ pump and also with 
the high-pressure city mains by means of hose. 


67 


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(See p. 69) 


Fig. 15.—Exterior of Spinning Mill, Maverick Cotton Mills. 


CHAPTER VI. 


MAVERICK COTTON MILLS. 


The Maverick Mills, constructed during the year 1910 at East Boston, 
Mass., were the first textile mills of large size in the United States to be built 
entirely of reinforced concrete. While ultimately the mills will operate 250,- 
ooo spindles, the initial installation is about one-quarter of this, and consists 
of a 51,200-spindle mill, 550 feet long, 130 feet wide, two stories in height; 
a 340 by 231 feet weave shed, one story high; a 30 by 4o feet two-story de- 
tached office building and a g1 by 62 feet power house adjoining the weave 
shed. 

The problem of installing the textile machinery on the concrete floors 
proved to be comparatively simple of solution, and it was found that the 
equipment could be set up fully as cheaply and with scarcely any more trouble 
than in a mill with wooden floors. This is partly due to the fact that the ab- 
sence of vibration and the greater friction between the bases of the machines 
and the concrete floor almost precluded any tendency for the machines to 
“creep,” which allowed a material reduction in the number of floor bolts. In 
the case of the spinning frames, for example, instead of the 22 floor bolts usu- 
ally needed, but six were required, and by using an air drill and expansion 
bolts these six could be placed almost as rapidly as six lag screws in a wooden 
floor. 

The exterior of the spinning mill is shown by the photograph in Fig. 15. 

The plant was designed by Lockwood, Greene & Co., engineers and archi- 
tects of Boston, Mass., and was built under their supervision according to the 
Hennebique System of reinforced concrete by the Hennebique Construction 
Company of New York. 

Reinforced concrete was used throughout the entire plant, the concrete 
being mixed in the proportions of 1:2:4. The stresses assumed in computing 
the sizes of the various members were 650 pounds per square inch extreme 
fibre stress on the concrete and 16,000 pounds per square inch tension in the 
steel, the ratio of the modulus of steel to that of concrete being taken as 15. 


SPINNING MILL. 


In the spinning mill, which was designed to carry a live load of 75 pounds 
per square foot, the columns are spaced in rows 25 feet apart transversely and 
ro feet 8 inches longitudinally. The story heights are 16 feet. The floor sys- 
tem consists of reinforced concrete girders spanning the 25 feet transversely 
from column to column and carrying a 41-inch floor slab of 10 feet 8 inches 
span. 

69 


Fig. 16 shows the detailed design of a typical girder. These girders were 
designed as fully continuous, the bending moment at both the center and over 
the supports being taken as 1/12 wl’. In order to provide for the excess com- 
pression in the concrete, at the bottom of the girder at the support caused by 
the continuous action, the girders were made deeper next to the support by 
forming a flat haunch as shown in Fig. 16. The girders are reinforced with 
two 14-inch and two 1%-inch round rods, the 1%-inch rods being bent up 
near the quarter points and carried horizontally over the supports into the 
adjacent bay. 

The stirrups, which are flat steel 4g inch by 34 inch, were bent in the 
form of a U and were placed as shown in Fig. 16. Near the support the stir- 
rups were inverted because, in a continuous beam in the part near the sup- 
port subjected to negative bending moment, the diagonal tension acts in the 
opposite direction to that in the part subjected to positive bending moment. 






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Fig. 16.—Details of Typical Beam, Slab and Column. 


The floor slabs, which are 414 inches thick, were also calculated with a 
moment of 1/12 wl? and are reinforced with 34-inch rods, 6 inches on centers. 
Cross reinforcing consisting of three 34-inch rods at right angles to the main 
reinforcing is provided in each bay to prevent shrinkage and temperature 
cracks and to stiffen the floor. 

The floors are finished with a 1-inch granolithic surface, composed of 1 
part cement to 1 part sand to 1 part %-inch stone, laid before the concrete 
below it had set, so as to form one homogeneous slab. 

All columns supporting the first floor are 18 inches square, those on the 
second 16 inches square and those running to the roof 14 inches square. The 


70 


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75 


reinforcing for these columns consists of four 54-inch rods bound with 4%-inch 
by 34-inch hoops spaced 12 inches on centers. 

The photograph in Fig. 17 illustrates the interior of the mill, and is espe- 
cially interesting in showing the heavy motors and shafting attached directly 
to the concrete above. 


WEAVE SHED. 


In the weave shed, which is only one story high with a basement, the col- 
umns are spaced 26 feet on centers longitudinally and 21 feet 4 inches trans- 
versely, every other column being carried through the first floor to support 
the roof construction. 

The floor, which is similar in design to that of the mill described above, 
was designed for a live load of 100 pounds per square foot. 

A particularly interesting feature in the design of the weave shed is the 
saw-tooth roof construction shown in detail in Fig. 18 and by the photograph 
in Fig. 19 of the interior of the building. 


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Fig. 18.—Cross-Section Detail of Saw-Tooth Roof. 


The inclined girders were designed as simply supported and were propor- 
tioned so as to have sufficient stiffness to obviate the necessity of horizontal 
tie rods from bay to bay. 

The total rise of the sawtooth is g feet 10 inches from the top of the col- 
umn to the peak of the roof. 

All the saw-tooth sashes are fixed and are double glazed. A wooden stool 
is bolted to the concrete sill and at the top a wooden blocking piece is attached 
continuously to the edge of the roof slab. The sash fits underneath this block- 
ing piece-and is attached to it by clamps and screws. The drip is taken care 
of by a beveled facia board placed over the top of the blocking piece and the 
top rail of the sash. 


72 





Fig. 19.—Interior View of Weave Shed, Maverick Cotton Mills. (See p. 72) 


Interior condensation is handled by a galvanized iron gutter supported on 
wrought-iron straps screwed to the stool, thence discharging into a 2-inch pipe 
running the width of the building in each bay. The drawing in Fig. 20 gives 
the detail design of the sawtooth sashes. 

Three-ply asbestos asphalt built-up roofing was used, this roofing being 
brought over the peak of the sawtooth and down over the facia board. 


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Fig. 20.—Details of Saw-Tooth Sashes, Maverick Cotton Mills. 


73 


POWER HOUSE. 


The power house, also of reinforced concrete construction, is divided into 
two parts by a longitudinal wall, one part being a boiler room one story high 
and the other a basement and one-story turbine room. The foundations of the 
boiler room are formed of wooden piles capped with reinforced concrete 
beams, while the engine-room foundation consists of a 22-inch reinforced con- 
crete mattress. 


74 


CHAPTER VII. 


LYNN STORAGE WAREHOUSE 


The Lynn Storage Warehouse, at Lynn, Mass., is built for the storage of 
general merchandise and furniture, reinforced concrete having been selected 
as the most economical fireproof construction. To provide for the variable 
character of its contents, the several floors are designed to sustain different 
loading; the three lower floors are each planned for the rather heavy loading 
of 250 pounds per square foot, while on the fourth floor 200 pounds per square 
foot of loading is to be allowed, and on the fifth and sixth floors 150 pounds. 
A possible weight of 50 pounds per square foot is provided for in the roof 
design. 

The building shown in Fig. 21 is six stories high besides the basement, 
being 50 feet wide by 165 feet long. Although not strictly speaking a fac- 
tory building, the design is typical of first-class factory construction. 

An interesting feature of the layout is the omission of the first floor in 
the corner of the building near the large elevator, in order to provide sufficient 
head room for teams to drive in and deposit their load upon the elevator, or 
else, if preferred, to drive directly on to the elevator, which is 11 x 12 feet 
in area, so that the wagon and horses can be elevated to the floor where the 
goods are to be placed and hauled to the proper point. 

The designers of the reinforced concrete and also the builders are the 
Eastern Expanded Metal Company, of Boston, Mr. J. R. Worcester being con- 
sulting engineer. The architect is Mr. D. A. Sanborn, of Lynn. 

A full cross-section of the warehouse, showing the dimensions of the 
members and the general scheme of design, is shown in Fig. 22. Fig. 23 
gives typical floor plan and also detail plan and section of the stairs. 


FLOOR CONSTRUCTION. 


Round rods are used for reinforcement of the beams ,girders and columns, 
while expanded metal* forms the slab reinforcement. 

The designs were carefully worked up by the Eastern Expanded Metal 
Company and checked by Mr. Worcester as consulting engineer. The sec- 
tional view (Fig. 22). clearly illustrates the general scheme of reinforcing. 
Complete details of a typical girder, beam and slab, designed to safely sustain 
150 pounds per square foot of the floor load in addition to the weight of the 
concrete, are drawn in Fig. 24 (p. 81). The slab, as indicated, is 6 feet in 


*See illustration, Fig. 22, page 77. 


75 


Fig. 21. —Lynn Storage Warehouse. 
76 





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Fig. 22.—Cross-Section Through Lynn Storage Warehouse. 


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78 


width from center to center of beam or 5 feet 3 inches in net span. The beams 
are 17 feet g inches from center to center of girders or 17 feet net span. The 
girders are 12 feet between centers of columns or 101% feet net span. 

The expanded metal reinforcement is placed near the bottom of the slab 
in the center of its span, and rises up to the top of the slab over the beams 
to provide for negative bending moment. The metal used is 3-inch mesh, 
No. 10 gage, this being equal to a cross-section of 0.175 square inches per foot 
of width of slab, or 0.5 per cent. of the cross-section of the slab area above 
the steel. 

-In the beams three 1-inch rods are imbedded, one of them bent up at the 
quarter points and running horizontally over the supports so as to lap by the 
rod from the next bay, thus giving two-thirds as much reinforcement over the 
supports as in the center of the beam. The stirrups are flat steel 4% inch by 
rt inch. Notice from Fig. 22 that in the three lower stories, where the loading 
is heavier, there are five stirrups in each end of the beam instead of two. The 
beams in these lower stories are made the same size, g inches by 20 inches, in 
order to use the same forms throughout the building, but the reinforcement is 
heavier. 

The typical girders in Fig. 24 have five 7%-inch rods at the center, two of 
them bent up and running on an incline from the center of the span. The in- 
cline starts at the center of the girder instead of one-quarter way from each 
end, because the girder having its greatest load at the center, the shear is 
nearly uniform throughout the entire span. 

Instead of the more usual practice of forming the wall girders as a part 
of the wall, they are built independently of the wall slab, as indicated in 
Hise 22: 


FLOOR SPECIFICATIONS. 


There are several points of particular interest in the floor specifications, 
and without copying them entire a brief outline is worth noting, as the data 
are quite full and the requirements conservative. 

The slabs are calculated with a bending moment 1/10 WL in cases where 
three or more slabs are continuous, while for the wall slabs 4% WL is em- 
ployed. The working strength of the concrete in compression is limited in 
the slabs to 500 pounds per square inch if computed by the parabolic method 
of stress, which is equal to about 600 pounds by the more usual straight line 
method. The slab steel is limited to 16,000 pounds per square inch in tension, 
the ratio of the modulus of steel to that of concrete being taken as 15. At 
right angles to the length of the span 1/10 square inch of steel is required per 
foot of length of slab, which with the 4-inch slab is equivalent to about 0.25 
per cent. A thickness of 34 inch of concrete is required below the metal in 
the slabs. 

The bending moment in the beams and girders is considered as 4% WL. 
The beams are considered as T-beams in computing their strength, and it is 
specified that the width of the flange shall not exceed one-third the span, and 


79 


that the average compression in the flange shall not exceed two-thirds of the 
extreme fiber stress. 

The vertical shear in the concrete in beams which are not reinforced for 
shear is limited to one-tenth the extreme compressive working stress in the 
concrete, and it is assumed that this vertical shear is distributed over a sec- 
tion whose area is the width of the stem, that is, the width of the beam multi- 
plied by the distance from the center of the steel to the center of the slab, 
the latter being considered as approximately the center of compression. In 
any case even when the beam is reinforced for shear the unit shear stress is 
limited to three-tenths of the extreme compressive unit fiber stress. Thus, if 
the allowable compressive fiber stress is 500 pounds per square inch, the shear 
in beams not reinforced for shear must not exceed 50 pounds, and in any case 
the section must be large enough so that even if reinforced there is sufficient 
area of concrete to keep the total shear stress within a limit of 150 pounds 
per square inch. 

When all of the shear cannot be taken by the concrete, the vertical com- 
ponent of the diagonal bent-up tension rods is figured to take it, and, in ad- 
dition, if necessary vertical or diagonal stirrups are introduced. 

The specifications required for the coarse material of the aggregate trap 
stone ranging in size of particles from ™% inch to 1%4 inches. The proportions 
for the floor system are 1:214:5, or by exact volume one barrel (4 bags) 
cement to 10 cubic feet sand to 20 cubic feet stone. 


FLOOR SURFACE. 


The floors are all finished with a granolithic surface 1 inch in thickness 
and this is included as a part of the slab thickness. Thus, if the plans require 
a 4-inch slab the lower three inches are 1:214:5 concrete, and the top inch is 
granolithic. The granolithic surface, which is composed of one part cement 
to I part sand to 1 part 1%-inch stone, is laid before the concrete below it has 
set, so as to form one homogeneous slab. 


TEST OF FLOOR. 


At an age of thirty days it is specified that a test may be made upon the 
floor panels with a total load two and one-half times the live plus the dead 
load. 


COLUMNS. 


The columns are spaced 12 feet apart lengthwise of the building and 17 
feet 9 inches on centers across the building. The interior columns supporting 
the lower floors are 24 by 24 inches and 25 by 25 inches (the larger size 
supporting the greater spans), and in the three upper stories the sizes are 
reduced to 17 by 17 inches and 18 by 18 inches. This arrangement was used 


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81 


to avoid remaking the column forms, this saving, in the opinion of the build- 
ers, being enough to more than offset the slight excess of concrete required. 

The columns are outlined in Fig. 24 (p. 81) and also quite distinctly in 
the general cross-section in Fig. 22 (p. 77). In the latter the diagonal rods 
will be noticed at the head of each column running into the beams and pro- 
viding diagonal reinforcement against wind pressure. The building is so 
high in proportion to its width that this reinforcement was considered ad- 
visable. 

The ordinary reinforcement of the columns is four 34-inch vertical rods, 
with occasional hoops % inch in diameter. In the wall columns, which are 
oblong in plan and which because of their location are subjected to a greater 
wind pressure, four larger vertical rods are inserted. The rods are of such 
length as to project above the next floor level, and the next set rests upon this 
floor so as to lap and transfer the stresses. 

The columns are laid with a richer concrete than other parts of the build- 
ing, being mixed in proportions 1:1144:3. The compressive stress allowed is 
700 pounds per square inch figured on the area of the column, or 600 pounds 
per square inch on the concrete if the steel is computed to take a proportion 
of the compression. 


CONSTRUCTION. 


Two very good construction views are presented in Figs. 25 and 26. 
Fig. 26 is taken after the completion of the concrete work of the fifth 
‘floor. The forms are removed from the columns and floor of the lower stories, 
but the supports are still left under the beams and girders of the fourth floor. 
The wall panels are completed in the first story and the forms for the second- 
story panels are in place on the side of the building. 

A photograph of the building complete is shown in Fig. 21 at the 
beginning of the chapter. 

The construction was begun about July 1, 1906, and was practically com- 
plete December ist, although the cold weather caused some delay beyond this 
time in completing the panels. The average rate of progress on the forms 
and structural concrete after the work was well started was ten days per story. 

The concrete was mixed on the ground in a rotary mixer, and 
a hoist elevated the concrete and dumped it into the hopper, from which 
it was conveyed by large two-wheel barrows and dumped in place. Approxi- 
mately 2,000 cubic yards of concrete were laid in the structure and 136 tons 
of steel were used in the reinforcement. This was delivered at the factory of 
the builders, where it was bent to the shape required, the ends of the tension 
rods being also bent hot at right angles to give a better grip in the concrete. 

In placing the steel the stirrups were set first, and as these were in the 
shape of a U with the ends bent over on a curve, these ends rested upon the 


82 


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Fig. 26.—Lynn Storage Warehouse with Roof in Place. (See p. 82) 


slab forms, thus forming a rest for the tension rods which were placed within 
them and supported at the proper distance above the bottom of the beam. 


FORMS. 


For the forms spruce lumber was generally employed. However, a good 
quality of North Carolina pine, tongued and grooved, was used for the panels, 
this being preferable to spruce because less apt to warp and having a harder 
surface, which splinters less and does not soak so much water. In all about 
182,000 feet board measure of lumber were used in the construction of the 
building. 

Only one set of forms was required above the first floor, the forms thus 
being used six times. Although a story was completed on the average in ten 
days, the work was carried on from end to end of the building, so that one 
end of the floor system had hardened sufficiently to allow removal of the forms 
for use in the floor above, while the other end of the floor was being laid. 
The beams and girder forms were constructed as U units, that is, the sides 
and bottom were fastened together, and by slightly beveling the sides the 
form was easily lowered. 

By reference to the plan in Fig. 22 (p. 76) it will be seen that although 
the allowable loading varied on different floors, the dimensions of the beams 
were maintained the same throughout except for those supporting the roof, 
the difference in the strength being provided for by varying the reinforce- 
ment. 

The general plan followed in removing the forms was to leave column 
forms two days, slab forms six days and beam forms six days. The shoring, 
however, was left under the beams and girders for three or four weeks to 
guard against possibility of accident. Of course these periods were varied 
according to the conditions of the weather and the hardening of the concrete, 
but they represent the ordinary minimum time. 

Petrolatum was used for greasing the forms. 

The usual gang consisted of one superintendent, 3 foremen, 8 men at the 
mixing, One engineman, 12 men placing concrete, 3 steel men and 30 to 60 
carpenters, the larger number being required for the first set-up of the forms, 
while the smaller number was sufficient for simply raising them to a floor 
above when there was no appreciable change in the design. 


WALL CONSTRUCTION. 


Panels were built as a separate operation from the rest of the concrete 
work, as shown in the photographic illustrations. The exterior columns were 
carried up at the same time as the floors, and the wall panels afterward filled 
in between them. The wall panel reinforcement consisted of 14 inch diameter 
rods, the horizontal rods being spaced 12 inches apart and the vertical rods 
24 inches apart. This steel was first placed, as shown in Fig. 26, and after 
setting the window frames, the forms, consisting simply of 2 inch by 4 


85 


SS 


inch studs with 1-inch boards nailed to them, were set, and the concrete pour- 
ed, running into grooves left in the columns. In Fig. 26 the difference in the 
color of the freshly laid and the old concrete is apparent, the concrete be- 
coming lighter as the water dried out. 


PARTITIONS. 


Around the elevators and stairs and also to enclose the offices on the 
first floor and storage rooms on the fifth floor, expanded metal partitions were 
employed. Expanded metal lathing, No. 24 gage, was wired to 1-inch channel 
bars placed vertically 12 inches on centers, and the lathing then plastered with 
five coats so as to form a solid partition 2 inches thick. 

The first or scratch coat consisted of one part cement to 3 parts of lime 
with the usual quantity of sand and hair. This pressed through the lathing, 
so that it could be plastered on both sides with a brown coat of lime and 
cement mortar in proportions 1 part cement to 3 parts of lime mortar and fol- 
lowed by a finishing coat of the same mortar on both sides. 


WATERPROOFING. 


To meet the requirement that the basement should be very dry, asphal- 
tum waterproofing was laid, as indicated by the solid black line in Fig. 22 
(p. 76) to prevent penetration of ground water. The ground having been 
thoroughly tamped, a layer of concrete was spread upon it and the wall slab 
placed. Then on top and inside of this layer of concrete, five-ply asphaltum 
waterproofing was spread and upon this 3 inches of concrete with granolithic 
surface. 


86 


CHAPTER VIII. 


WINCHESTER REPEATING ARMS FACTORY. 


The new Loading buildings of the Winchester Repeating Arms Company 
located on their property between Winchester Avenue and Sheffield Avenue, 
in New Haven, Conn., are especially interesting because of the heavy loads 
actually carried and the fact that flat-slab or girderless floors, sometimes called 
the mushroom system, were adopted instead of the ordinary plan of short-span 
slabs, supported by beams and girders. 

In this flat-slab construction, which is illustrated by the photograph of 
the interior of the building in Fig. 30 (p. 90) and by the details of design in 
Fig. 28, no beams are used, the floor being of uniform thickness throughout 
and the loads transmitted from the floor slab direct to columns with flared 
capitals. The absence of the beams that tend to cut down the head room, 
obstruct light, gather dust, and interfere with the convenient arrangement of 
the shafting and pulley supports, goes far to make this for many purposes an 
ideal form of factory construction. 

The loading buildings are duplicates with the exception of a steel-frame 
plaster-walled storage room on the roof of one, and they are connected by a 
corridor opening off the elevator well and toilet rooms that serve both build- 
ings. Each building is 300 feet long, 60 feet wide, two stories high and de- 
signed with sufficient strength to provide for two additional stories in the 
future. 

The buildings were erected by the Aberthaw Construction Company, of 
Boston, who also designed the structural features. The architect was Mr. 
L. W. Robinson, of New Haven, Conn. 

The photograph in Fig. 27 (p. 88) shows the completed buildings. 


DESIGN. 


The second and future third-story floors were designed to carry a live load 
of 250 pounds per square foot over the entire area, while the other floors 
throughout the buildings, including stairs, landings, platforms, etc., were de- 
signed for a live load of 150 pounds per square foot. 

The columns are spaced 20 feet by 24 feet on centers. 

All floor slabs, which were designed according to the MacMillan method, 
are 10 inches thick and reinforced by bands or sets of 34-inch round rods 
running in four directions radially from the column heads. The spacing of 
these rods, together with the arrangement of the radial bars, is shown by the 
partial second-floor plan in Fig. 28 (p. 89). 


87 


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The end panels are supported by reinforced concrete beams running be- 
tween the exterior columns. These beams, a typical one of which is shown in 
detail by Fig. 29, also carry the brick panel beneath the windows. 


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Fig. 28.—Plan Showing Floor Reinforcement, Winchester Repeating Arms Loading 
Building. (See p. 87) 


In calculating the strength of the flat slab and of the wall beams the ratio 
of the modulus of elasticity of steel to that of concrete was taken as 15, the 
concrete was figured at 625 pounds per square inch fibre stress and the steel in 
tension at 14,000 pounds per square inch. 


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Fig. 29.—Details of Typical Wall Beams. (See p. 90) 
89 


The columns, shown in detail by Fig. 29 (p. 89) are composed of structural 
steel plate and angle columns incased in concrete. This structural steel work, 
designed to carry the entire live and dead loads of the floors above, together 
with the weight of the columns themselves, was computed on the basis of 
Gordon’s formula, which gave a stress of approximately 12,000 pounds per 
square inch. Fig. 29 (p. 89) shows the details of the flared column heads and 
the arrangement of the radial bars and circular hoops which support the slab 
reinforcement. 

Throughout the entire work the concrete was mixed in the proportions 
of 1 part Atlas Portland Cement to 2 parts sand to 4 parts broken stone. 





Fig. 30.—Interior of Loading Buil7ing, Winchester Repeating Arms Company. 
(See p. 87.) 


In the first story the finished floors are of 14-inch tongued and grooved 
maple flooring laid on 3 by 6-inch spruce planks bedded on “Tar-Rok.” The 
second story finished floors consist of 14-inch tongued and grooved maple 
flooring with an under floor of 2 by 6-inch tongued and grooved spruce plank 
secured to 3 by 3-inch spruce screeds placed 20 inches on centers and em- 
bedded in 3 inches of cinder concrete fill. 


CONSTRUCTION. 


The two buildings being in every respect identical, it was decided to erect 
them with two distinct competing gangs. In order that the test might be 


go 


absolutely fair, duplicate equipment was furnished for the two sides, and the 
foremen in charge of the two buildings were allowed to select their labor 
bosses, carpenter foremen, and, within reason, to have a free hand in the num- 
ber of carpenters and laborers that were to be employed on their respective 
buildings. Two Smith concrete mixers were placed side by side on the Win- 
chester Avenue end of the buildings so that the two concrete gangs worked 
from the same stock piles and were side by side. 

From the very start of the job rivalry between the two sides began to grow, 
and at completion cf the work, when it was only a question of hours as to 
which side would be the winner, the competition was so earnest that a free- 
for-all ight between the contending gangs was barely averted. At the ebegin- 
ning of the work it was considered tha a good day’s concretig had been done 
when two bays of length of floor had been cast the width of the building. At 
the end of the job the men put in three bays in eight hours, an increase of 
over 50 per cent., part of which could be charged to experience in handling the 
work, but a large amount to pure rivalry. 

The work was started in July, 1909, and finished in December of that 
year. 


COST. 


The total cost of the building including excavation, was about $150,000. 
The cost of the concrete in place was $6.00 per cubic yard. The forms cost 
12'%4 cents per square foot and the reinforcing steel $45 per ton in place. 


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92 


CHAPTER IX. 


BULLOCK ELECTRIC MACHINE SHOP. 


A novel feature of the reinforced concrete machine shop of the Bullock 
Electric Company, at Norwood, Ohio, a branch of the Allis-Chalmers Com- 
pany, is the supporting of 10-ton cranes upon concrete brackets which form 
a part of the concrete column. It is customary even in reinforced concrete 
shops to place the crane runs upon steel columns independent of the rest of 
the structure, but we have here an example of the transmission of the load 
directly from the runways, which are steel plate girders, to the reinforced 
concrete columns. The machine shop, illustrated in Fig. 31, was only fifty- 
eight and a half days in building and has been in successful and continuous 
operation since its completion early in 1906. 

The building under consideration is an extension to Shop No. 3, which 
is of the regular type of steel frame with brick walls. The extension was 
first designed in similar steel construction, but an alternate proposal to sub- 
stitute reinforced concrete made by the Ferro-Concrete Construction Com- 
pany, of Cincinnati, was adopted at substantially the same cost. 


DESIGN. 


The general design of the building is shown in the cross-section in Fig. 
32, and a partial elevation in Fig. 33. 

The lower story is devoted to the manufacture of the heavier part of the 
electric machinery and in the assembling of dynamos. In the upper story 
are the lighter machine tools for the making of the smaller parts. The roof 
is of 2-inch plank upon steel trusses (see Fig. 32), being built in this way in- 
stead of in reinforced concrete so that it can be raised and a third story added 
when needed. One end of the building, as shown in the photograph of the 
completed shop, Fig. 31, is also of temporary construction, so that it can be 
lengthened without tearing down a brick and concrete wall. 

Twisted steel was used for reinforcement. The proportions of the con- 
crete were 1:2:4 throughout, using 4 bags Atlas Portland cement to 8 cubic 
feet of good coarse sand to 16 cubic feet of broken stone, which was the run of 
the crusher, screened through a 14-inch screen. 

The floors (see Fig. 38) consist of three longitudinal bays running the 
entire length of the building, a distance of 256 feet. The total width is 107 
feet 714 inches, thus allowing the two outer bays to be each 42 feet 1114 
inches and the inside bay 21 feet 814 inches. In the other direction, that is, 


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94 


lengthwise of the building, the columns are 16 feet apart on centers. The 
long open floor spaces afford ample room for the machine tools and the hand- 
ling and distributing of the parts and the finished machines. A view of the 
shop in operation is photographed in Fig. 34. 

The height of the first story, 27 feet in the clear from the floor to the 
ceiling and 23 feet in the clear to the bottom of the girders, provides the head 
room necessary for the 10-ton cranes which are located in the outside bays, 
and also permits very large high windows. 

The center bay is designed so that another crane may be installed there 
when required, but for the present its place is occupied by an intermediate 
floor. This floor is of light steel I-beam and wood construction, resting upon 
channel irons running across between the two rows of columns. The chan- 
nels are bolted at the ends to the concrete columns and their weight also sup- 








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SIDE ELEVATION. | 
Fig. 33.—Side Elevation of the Bullock Machine Shop. (See p. 99) 
ported by straps suspended from the crane brackets. Had the floor been in- 
tended for permanent use it would have been built of reinforced concrete, but 


the difficulty and expense of tearing down a floor of concrete when the space 
was needed for the crane made this impracticable. 


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COLUMNS. 


Footings of the interior columns are shown in Fig. 35. These illustrate 
a typical reinforced concrete footing with two layers of rods at right angles 
to each other in the bottom. In this case the rods are 34 inch diameter, while 
in the footings for the wall columns, which are not shown in our drawings, 





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'4-inch rods fulfil the requirements. The rods in each layer are shorter than 
the dimensions of the footing in the interior columns (Fig. 35), being 6 feet 
8 inches long and placed with one end 2 inches from the edge of the footing 
and the other end 18 inches from the opposite edge, the alternate rods being 
staggered to allow for the decrease in the bending moment from the column 
toward the edges of the footing. As the footing is square, while the column 
is oblong, 10 bars run in one direction, while 12 bars are placed in the other 
layer to provide for the greater bending moment. 

The footings really extend up to within 3 inches of the first floor level 
the short vertical section of 2 feet 11 inches being built at the same time as 
the footing proper in order that the first floor can be laid entire and the first 


97 


story columns started above it. These short vertical lengths are reinforced 
with six 1-inch rods which extend 4 inches down into the main part of the 
footing and project 7 inches above the concrete so as to pass through the 
floor and connect with the column above. These vertical rods rest upon steel 
plates 3 inches square, which distribute the compression from the steel to the 
concrete. Four %-inch horizontal hoops are placed around the vertical rods. 
The columns above the first floor are of slightly smaller dimensions, as shown 
by the offsets in Fig. 32. Thus, the portion below the first floor is 21 by 27 
inches, which reduces to 18 by 24 inches with a further reduction above the 
crane brackets. The reinforcement in the columns in the first story is the 
same as below the floor, six 1-inch rods butting upon the ends of the rods be- 
low and connected with them by a short pipe sleeve. One-quarter-inch hoops 
were spaced, double, every 12 inches. 

The wall columns have footings similar to those of the interior columns, 
except of smaller dimensions and lighter reinforcement. The base is 7 feet 
4 inches, reinforced with sixteen 14-inch rods in each layer. Below the first 
floor the column is 20 inches by 26 inches, reinforced simply with a 34-inch 
rod in each corner and four 14-inch horizontal hoops. 

Above the first floor the exterior columns are of T-shaped cross-section, 
as described in the paragraphs which follow, the column proper being 14 by 
22 inches in the first story and 12 by 14 inches in the second story. 


CRANE BRACKETS. 


The brackets, shown in Fig. 32 (p. 94), which support the cranes are of 
particular interest. To provide for the shear, it was considered advisable to 
loop the reinforcing rods into the bracket, running them out horizontally and 
then bending them down on an incline back into the column. The steel I- 
beams supporting the track for the crane rest directly upon these brackets 
and run the full length of the building. 


FLOOR SYSTEM. 


The floor of the first story was laid directly upon the ground after filling 
in around the columns and thoroughly puddling the earth. This floor is of 
1:2:4 concrete with sleepers upon it and a 2-inch oak floor. 

The second floor is supported in the two bays by girders about 4o feet 
long in the clear, 12 inches wide and 541% inches deep from top of slab. In 
the bottom of the girder, to take the tension, are ten 1-inch square twisted 
rods and, to provide for the negative bending moment, five 1-inch rods were 
placed: at the top of the beams over the supports. The shear or diagonal 
tension is provided for by these bent-up rods, together with sixteen 14-inch 
and ten %4-inch U bars. The reinforcement was rigidly located before the 
concrete was poured, so that it could not be displaced. 

In the central bay the net span is about 20 feet and the girders are smaller, 
being 6 by 31 inches. The thickness of the slab is included in the depth 


98 


of the girders in both cases, since the concrete for the girders and slabs was 
poured at one operation. 

The girders extend across the building from column to column, and are 
thus 16 feet apart on centers, giving a net span for the concrete floor slab of 
15 feet in the outside bays and 15 feet 6 inches in the middle bay. The slabs, 
which are designed by a load of 225 pounds per square foot, are 774 inches 
thick, reinforced with 14-inch bars spaced 6 inches on centers. In addition 
'%-inch rods about 2 feet apart run-across the building parallel to the girders 
to prevent contraction cracks. 

The wearing surface of the floor is 74-inch maple flooring upon 3 by 
4-inch sleepers spaced 16 feet apart on centers and filled between with cinder 


concrete. 
WALLS. 


The window area comprises a large percentage of the wall surface, the 
openings in the concrete being 12 feet 2 inches wide and in the lower story 





Fig. 36—Tongs for Bending Light Steel Bars. (See p. 102) 


23 feet 8 inches. The walls, 4 inches in thickness, were carried up at the 
same time as the columns, thus forming with them T-sections, as shown in 
Section GG, Fig. 33. Below and above the windows, the wall was also 4 inches 
thick, with water table and sills, as in Fig. 33. The window sills, which are 
5 inches thick, were poured as a part of these walls and were thoroughly 


99 


troweled on the top before the concrete had set hard, so as to form a surface 
like that on a sidewalk. 

Each vertical section of wall was reinforced with two 14-inch square bars 
in the first story and two %-inch bars in the second story. Horizontal loops 
of 14-inch wire were also placed about 2 feet apart. Above the windows the 
walls were reinforced with three horizontal rods and with vertical rods spaced 
about 3 feet apart. Fig. 33 (p. 95), which is a side elevation of two bays, 
illustrates more clearly the placing of the wall reinforcement. 

In order that the exterior of the new building should harmonize with the 
older shops in the same plant, the walls were surfaced with a single thickness 
of light-colored pressed brick. These were tied to the wall by the wires which 
were used in keeping the forms together. These ties were No. 8 galvanized 
iron wire about 12 inches long, which projected from the concrete about 6 
inches. They were spaced every 18 inches horizontally and every six courses 
of brick vertically. The projecting ends were turned in a hook by the brick- 
layer and bedded in the mortar joints just like regular brick anchors. 


CONSTRUCTION PLANT. 


In accordance with their usual plan in building construction, the con- 
tractors erected near the site a carpentry shop about 20 feet by 42 feet, with 





FACE SIAVE 


Fig. 37.—Power Bender for Large Steel Bars. (See p. 102) 


an adjoining tool room. In the shop, wood-working tools, including a circular 
saw and a planer, were installed and driven by electric motor from power 
furnished by the town plant. Here all the forms were prepared. 


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The steel was also bent in this shop. For the small rods of the floor slabs 
a heavy pair of tongs was used, with three projecting lugs, as shown in Fig. 
36 (p. 99). The heavy steel for the beams and girders was bent by power in 
a machine consisting essentially of a face plate with a roller projecting from it, 
which, when the power is applied, bends the bar around the spindle. The 
sketch in Fig. 37 (p. 100) illustrates the operation. 

The layout of the construction plant and its relation to the machine shop 
are illustrated in Fig. 38. The broken stone, sand and cement were brought 
in railroad cars and stored in bins close to the tracks. The mixing plant was 


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Fig. 39.—Sectional Plan and Elevation of Girder Molds. (See p. 104) 














provided with both a Ransome and a Smith mixer, although most of the time 
one of these machines was of sufficient capacity to supply the concrete. The 
materials were wheeled along the runway on the platform, from which they 
were dumped into the mixers. From the mixers the concrete was brought to 
the place where used, in two-wheel barrows of Ransome type, but with stag- 
gered wheel spokes, these having been found to be better than the single row 
of spokes. Each of these held about 5 or 6 cubic feet of concrete. The hoist 
consisted of a single platform double-barrow hoist, taking two barrows up 
at one time, and from the hoist the concrete was wheeled to place upon a 
runway raised above the steel, so as not to interfere with it, and dumped 
directly in place. 

The cost of the construction plant, not including small tools, shovels, etc., 
was $4,350. In the building 2,300 barrels of cement were used. 


102 


GANG. 


The usual gang consisted of about fifty laborers and fifty carpenters. 
The men engaged directly upon the building were distributed approximately 
as follows: 

Four foremen. 

Twelve men mixing concrete. 

Six men hoisting concrete. 

_ Fifteen men placing concrete. 

Seven men bending and placing steel. 

One engineman. 

Fifty carpenters. 

The regular rate of pay for the laborers, who were experienced concrete 
men, was $2 per day of ten hours. 


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Fig. 40.—Details of Column Molds. (See p. 104) 


FORMS. 


The forms were built of yellow pine, which cost $20 per thousand. As 
the building was only two stories high, much of the lumber could be used only 
once, although some of the wall and column forms were used twice. The 
lumber cut to such good advantage, however, that much of it could be used on 
another job, and the builders estimated the salvage at about 30 per cent., that 


103 


is, it might be assumed that three-fifths of the lumber could be used to good 
advantage on another building, and that the value of this was one-half of its 
original price. 

The panel boards were planed one side and on the edges. For the beam 
and column molds 1 by 6-inch tongued and grooved stock was employed. 

The construction of the girder molds is shown in Fig. 39 (p. 102), and the 
column molds more in detail in Fig. 40. The column bands or clamps were 
2 by 4-inch stuff, held together by blocks and wedges, as shown in the draw- 
ing. On one side the piece was loose, so that the same clamp could be used 
for a narrower column by changing the position of the blocks. The clamps 
were spaced 18 inches apart near the bottom of the column, reducing to 24 
inches apart near the top. 

The girder forms consisted essentially of 1-inch paneled sides, the boards 
battened together with pieces of 2 by 4-inch stuff, and a bottom of 134-inch 
plank, which was supported in part by 1 by 3-inch cross pieces nailed to the 
end of the batten strips, and in part by the shores or struts resting upon the 
floor below. A 1 by 6-inch strip nailed to the upper part of the battens sup- 
ported 1 by 6-inch joists, upon which rested the slab flooring. 

The shores or struts, instead of being a single piece of lumber, were 
made of I-section by nailing together three pieces of 2 by 6-inch plank, as 
shown in section AA, Fig. 39. This plan was followed because the first story 
was so high that an ordinary 4 by 4-inch post would have been liable to spring 
unless braced very frequently in its height. 

The forms of the walls, columns and panels were left in place about two 
weeks and the shores six weeks. This time was longer than is customary, 
but in this building the spans were so long that the dead weight of the con- 
crete was exceptionally large, and this threw a large proportion of the total 
load upon the concrete when the forms were first taken down. 


CHAPTER X. 


FACTORY OF HUNTER ILLUMINATED CAR SIGN COMPANY. 


The factory building of the Hunter Illuminated Car Sign Company, 
erected in 1911, at Flushing, L. I., is built with walls of hollow tile. 

The hollow tile used in the construction are called “Tilecrete” and are 
manufactured under the “Pauly Process.” By this process the concrete, com- 
posed of Portland cement and carefully selected aggregates and mixed to the 
consistency of grout, is poured into molds surrounded by a steam jacket. 
Enough water is evaporated from the concrete by the heat to permit the 
withdrawal of the tile within a few minutes, although enough water is left 
to thoroughly harden the tile. The finished product has the density and uni- 
formity of wet mixed concrete and is very true and uniform in shape and size. 

While the tile itself is remarkably cheap, it is in erection that the greatest 
economies are obtained, as the large size of the tile enables a given volume 
of wall to be erected with fewer units than with any other materials. Ex- 
perience has demonstrated that a mason can easily lay 400 10-inch tiles per 
day, thus erecting eight times as much wall as would be possible with brick. 

The building, an exterior view of which is shown in Fig. 41 (p. 106) was 
designed and constructed by the Concrete Products Company of New York 
City. 


DESIGN. 


The building is 80 feet long and 75 feet wide, two stories in height with 
a one-story office addition 21 by 31 feet. The side walls of the main building 
are 22 feet high and the gable walls 31 feet high. 

The floors are of wood, the first floor being supported on Lally columns 
and the roof on wooden posts. The sills and lintels are all of reinforced 
concrete built in place. 

The partial plan and sections in Fig. 42 (p. 107) show the details of design. 


CONSTRUCTION. 


After the footings were put in the foundation walls were built up of con- 
crete hollow tile 12 by 16 by 12 inches, pointed and filled with concrete, so as 
to form a 16-inch solid wall without the use of wooden forms. The main 
walls were then carried up in 8-inch hollow tile broken out in pilasters on 
the side walls 15 feet on centers and on the gable walls 18 feet 6 inches on 
centers. 

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107 


The pilasters thus are 16 inches by 32 inches and in order to form col- 
umns were filled solid with concrete and reinforced with 34-inch steel rods. 

After the building was completed the tile were carefully pointed on both 
sides of the wall and the faces cleaned down, so that at a short distance away 
the work has the appearance of dimension stone. 


COST. 


The building cost complete, including heating and plumbing, about 
$10,000 or approximately 75 cents per square foot of floor surface. 


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109 


CHAPTER XI. 


WHOLESALE MERCHANTS’ WAREHOUSE. 


The immense reinforced concrete warehouse at Nashville, Tenn., illustra- 
ted on page 109, Fig. 43, is the result of a scheme of co-operation of a number 
of the most prominent merchants of that city. They previously had con- 
ducted their business in various individual warehouses in the business sec- 
tion of the city and some distance from the railroad. To better their condi- 
tion the idea was conceived of forming the Wholesale Merchants’ Warehouse 
Company to erect a fireproof building alongside of the tracks, and thus save 
the large expense of hauling and at the same time obtain greatly reduced 
insurance rates. 

Insurance on the stock carried by the merchants in the old type of frame 
buildings ranged from $1.80 to $2.20 per hundred while in the new fireproof, 
reinforced concrete structure the rates were reduced to $0.40 per hundred. 

- To provide enough floor space not only for storage but also for carrying 
on the wholesale shipments, the building is 500 feet long by 132 feet deep 
and four stories high, with basement and sub-basement. It is divided by 
walls of concrete blocks into compartments entirely separate one from the 
other, each compartment comprising a complete wholesale warehouse, and 
as:the building is located not only near the railroad but in the central part of 
the city as well, it constitutes the sole place of business in the city for each 
firm. 

:« The basement is paralleled by two railroad tracks, an extension of the 
basement floor forming the unloading platform. A wide trucking platform 
also runs through the basement, reaching all the elevators. 

_ Reinforced concrete was adopted because of the estimated economy in 
cost and in time of construction. The designing architects were Messrs. Mc- 
Donald & Dodd; the supervising architect, Mr. Hunter McDonald, and the 
engineer, Mr. W. H. Burk. The Oliver Company were the builders. 

Corrugated bars* were used throughout the building, and the Expanded 
Metal and Corrugated Bar Company approved the plans as drawn. 


LAYOUT. 

The general plan, Fig. 44 (p. 112), is a framing plan showing the layout 
of the beams and also illustrating the division of one of the floors into the 
compartments for the different firms. The interior columns are spaced 12 feet 

*See Fig. 113, page 194. 


IIo 


apart in one direction and 16 feet 714 inches in the other. In general, the 
beams run lengthwise of the building from column to column, with no sup- 
porting girders, while cross beams are placed at intervals to tie the building 
together and to support the partitions. 

These cross beams and their partitions are not spaced uniformly, but at 
different distances apart, so as to afford a merchant a choice of several sizes 
of rooms, each of which extends the full depth of the building. For example, 
the spacing of the partitions is three bays in a large number of cases, while 
in one portion of the building the spacing is one and a half bays; in another, 
two bays; and in still another four bays. The widths of the compartments 
thus vary from about 24 feet to 66 feet, with a uniform depth of about 130 
rect. 

The beam design is somewhat different from usual along the front and 
rear of the building. Here the cross span is 18 feet instead of 12 feet, and 
short cross girders are introduced, each of which supports a floor beam at its 
center. The projecting girders at the rear of the building, that is, at the top 
of the plan in the figure, support the roof over the loading platform in the 
basement. 

A cross section of the building is given in Fig. 45 (p. 112), showing the 
columns and the outline of the beams and slabs. In order to take advantage 
of the full width of the lot, and yet not encroach upon the loading platform 
with the basement columns, the rear wall of the building from the first floor 
up to the roof is supported by the ends of the floor girders which project at 
each story about 30 inches, thus acting as cantilevers. 

Because of the variety in the weights of the goods to be stored, the floors 
were designed for different loadings. The first floor was calculated for 350 
pounds loading per square foot of surface, the second floor for 300 pounds 
and the third and fourth floors for 250 pounds. The roof was figured for a 
snow load of 40 pounds per square foot. These figures in each case represent 
live loads, and do not include the weight of the concrete itself. 


BEAMS AND SLABS. 


Details of the construction of a typical beam and slab are drawn in Fig. 
46 (p. 113). These are designed for the first story to support a floor load of 
350 pounds per square foot in addition to the weight of the reinforced con- 
crete itself. 

Inspection of the plans shows that three of the six bars in the beam are 
bent up on an incline and run across over the supports, lapping there a dis- 
tance of one-quarter of the span length. Several 3/16-inch round stirrups 
are also provided to assist in taking the shear. The dimensions of the beams, 
12 by 20 inches for the longitudinal beams of which the details are shown, 
and ro by 16 inches for the cross beams supporting the partitions, are given 
in the customary way, measuring the depth from the top of the slab to the 
bottom of the beam, and assuming, of course, that the standard practice is 


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followed of placing the concrete in the beams and slabs at one time, so as to 
form a monolithic T-section. The rods in the bottom of the beam are placed 
in two layers, so as to bring them far enough apart to prevent the concrete 
splitting between them. 

It will be noticed in the floor sketched, that 14-inch bars 5 inches apart, 
to form the reinforcement for the slab, are placed in the bottom of the slab 
at the center of its span, but that all run up toward the supporting beam, and 
thus in the longitudinal section of the beam at the top of the diagram these 
rods, which are shown by so many dots, are close to the upper surface. This 
plan is somewhat easier to follow than where rods are alternately horizontal 
and bent up, and it is preferable to the latter because the negative bending 
moment at the ends of a continuous slab is at least as great as the positive 
moment in the center, so that fully as much reinforcement is required to take 
the pull at the top of the slab over the supports as is necessary in the bottom 
at the middle of the span. 

The roof is of concrete of lighter design, and the slab, which is 3 inches 
thick, is laid on a slope of %-inch per foot and is covered with tar and gravel 
roofing. 

A detail of the beams around elevator walls is drawn in Fig. 46. 








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Fig. 46.—Details of Reinforcement of Typical Beam and Slab. (See p. 111) 


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COLUMNS. 


Although the floor loads are heavy, the columns are only 19 inches square 
in the basement and less than this in the stories above because the spacing 
between them is comparatively small. The general type of reinforcement is 
four 54-inch vertical bars near the corners with 3/16-inch horizontal loops at 
intervals of 5 to 12 inches, varying with the dimensions of the columns, In 
the first story 34-inch vertical bars were used with loops 4 inches apart. 

The columns are designed for a loading of 750 pounds per square inch, 
a seemingly high stress for the proportions of cement to aggregate used, 1: 
2%4:444, but in making the calculations no account is taken of the area of 
concrete outside of the steel loops nor of the strength of the vertical steel, so 
that the loading is really conservative. 


113 


WALLS. 


For the walls a skeleton structure of columns and beams is carried up, 
as shown in the photographs, and filled in with brickwork, the outside face 
of the columns being veneered with brick so as to give a uniform surface. 
The exterior trimmings and the doors and window sills are all artificial stone. 

The interior or partition walls, which separate the compartments into 
which the floors are divided, are of concrete blocks supported upon reinforced 


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Fig. 47.—Detail of Framing at Elevator. (See p. 113) 





The concrete blocks were made of 1 part cement to 114 part sand to 4% 
part crusher dust. They were made in Hercules facedown machines and 
were faced on both sides during the process of the making with a layer of 
1 to 2% mortar. The standard size blocks in the partition walls were 8 by 8 
by 24 inches, with two hollow spaces; the blocks around the elevators were 4 
by 4 by 6 inches solid. Rabbets were formed in each end and in top and bottom 
surfaces, and filled with cement mortar as the blocks were laid, in order to 
secure as perfect a bond as possible. No interior plastering was used in the 


114 


building except in the offices of each warehouse, which usually occupied only 
a small part of the first floor. The first two floors of the building outside of 


the offices were whitewashed by machines. The rest was left without any 
finish. 


STAIRS. 


Stair details are shown in Fig. 48. The stairways are of straight run 
from story to story, and consist of a slab with the upper surface formed into 
steps. The bottom of the slab is reinforced with 14-inch bars placed 2 inches 
apart, and 14-inch rods also run across the steps at occasional intervals. The 
foot and head of each flight is especially reinforced, as shown, to strengthen 
it at the ends and connect it with the floor system. 


COAL TRESTLE. 


Reinforced concrete coal trestles are occasionally built, but comparatively 
few designs have been published, and the trestle erected in connection with 
this building is therefore shown in considerable detail. Its elevation is given 
in Fig. 43 (p. 109) and the details in Fig. 49. 

Two railroad tracks are carried by the trestle and most of the surface is 
Hoored over, the slabs being sloped to drains. 














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CONSTRUCTION. 


The warehouse was about eight months in building, and during this period 
11,830 ‘cubic yards of concrete were placed; of this 8,398 cubic yards were re- 
inforced and 3,432 cubic yards plain. The latter figures included the blocks. 

-The mortar finish for the floors measured in addition 510 cubic yards. 


115 


Amount of cement required was as follows: 


Reinforced concrete, 10,365 barrels. 
Floor finish, 1,690 barrels. 
Artificial stone, 99 barrels. 

Plain concrete, 1,770 barrels. 
Concrete blocks, 4,051 barrels. 
Total, 17,975 barrels. 


The work in progress is shown in photograph, Fig. 50. 





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Fig. 49.—Details of Coal Trestle. (See p. 115) 


The concrete was supplied to the different parts of the building by a 


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building and far enough away from it to leave room for the construction plan 
between. 

The outline of the building with the cableway and construction plant is 
sketched in Fig. 51. The building rests on ledge, so that it was necessary to 
excavate a large quantity of rock, and the stone taken out was utilized in the 
concrete and also in the concrete blocks. This necessitated the installation 
of a crushing plant, a somewhat unusual feature in building construction, but 
which was made possible by the large amount of ground space and by the fact 
that the broken stone and screenings not only could be utilized for the build- 
ing, but because there was a demand for the sale of the surplus coarse mate- 
rial for railroad ballast. 

Crushers were set to crush the stone to maximum size of 114 inch and the 
dust up to %-inch was screened out for use in the concrete blocks. All the 
rest of the crushed material was used in the concrete without further grading. 
Sand used on the work was brought in from Memphis in cars, while for the 
floor finish the aggregate was crushed granite. 

A No. 4 Smith mixer made the concrete, and this was fed with material 
by a stiff-legged derrick having a 65-foot boom and operated by a 4-drum 
Lambert engine. The bucket was of a 114-yard clamshell type, and dumped 
the material into charging bins which measured the materials automatically. 
The concrete fell from the mixer into buckets which were taken by cable and 
transported to steel portable bins located on the floor of the building where 
the concrete was laid, and whence it was finally delivered by Ransome 2-wheel 
carts. The highest run of the plant was 383 cubic yards in ten hours. A 
diagram of the mixing plant is given in Fig. 52. 

The cableway also handled lumber for the forms and mortar for the floor 
finish, which was put on as the concrete was laid. 

The plan of the plant also locates the lumber yard and carpenter shop 
at the other end of the building from the concrete plant. The forms were all 
made here, as much of the work as possible being done by machinery. 

The cost of the lumber for the forms, which were used from four to eight 
times, was $5,400 and the salvage is figured at about 20 per cent., i. e., it is 
estimated that the value of the lumber left over which would be suitable for 
another job was about 20 per cent. of the original cost or about $1,100 and 
that this amount could be deducted when charging up the lumber to this 
building. Pine lumber was used throughout, and for panels it was tongued- 
and-grooved. The forms were left in place for about 25 days. 

At one end of the building all of the reinforcement was stored, and forges 
operated by compressed air from the signal plant of the N. C. & St. L. Ry. 
were so arranged that they could be set at required points and the girder bars 
which required bending thus heated and bent in four places at the same time. 
Special benders were used for shaping the small rods. The column reinforce- 
ment was assembled and wired together before being placed in the form, 
special care being taken to accurately place it. The cost of bending and plac- 
ing the steel was 0.4 cent per pound. 


119 





WEF F7EE/ 
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Fig. 52.—Mixing Plant. (See p. 119) 


120 





I21I 


(See p. 122) 


Fig. 53.—Interior of Wholesale Merchants’ Warehouse. 


The construction gang consisted in general of three foremen, 3 men mix- 
ing, 32 men placing, 45 carpenters, 20 steel men, 9 enginemen, besides some 
60 to 150 men on the excavation and from to to 40 men on the stone crushing. 


A photograph of the interior, showing the columns and floor system, is 
given in Fig. 53. 


COST. 


The entire cost of the building was about $357,000 including finish, of 
which $192,000 was for the reinforced concrete and the excavation. The cost 
of the construction plant, which is included in these sums, was $19,000, an 
unusually large amount, but probably warranted in this case by the size of 
the building and the need of a crusher plant. 


I22 


Eo 


CHAPTER XII. 


PLANT OF BOSTON WOVEN HOSE AND RUBBER COMPANY. 


The plant of the Boston Woven Hose & Rubber Company, located in 
Cambridge, Mass., includes a hose manufacturing building and two ware- 
houses of reinforced concrete covering approximately 220,000 square feet of 
floor space. , 

An interesting feature in connection with these buildings is the speed with 
which they were erected, the work being started on July 19, 1907, and com- 
pleted ready for occupancy by the middle of October, only thirteen weeks be- 
ing required. Such a record would have been absolutely impossible with any 
other type of construction than reinforced concrete. 





Fig. 54.—Interior View of Hose Building. (See p. 125) 


The plant was designed by Mr. John O. DeWolf, Architect and Engineer, 
of Boston, Mass., with Mr. Edward A. Tucker, Boston, Mass., as concrete 
engineer, and Mr. Sanford E. Thompson, Newton Highlands, Mass., as con- 
sulting engineer, the contractor being Benjamin Fox, of Boston, Mass. 


123 


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124 


An exterior view of the completed plant is shown in the photograph, Fig. 


55 (p. 124). 
DESIGN. 


The hose building is 322 feet long by 60 feet wide, with four stories each 
15 feet high from top of floor to top of floor. A single row of columns spaced 
1o feet 4 inches on centers runs through the center of the building. The floor 
system is made up of reinforced concrete girders spanning across the building 
30 feet from the interior columns to wall pilasters and carrying a 5-inch floor 
slab. 

The photograph in Fig. 54, (p. 123) shows the interior of this building. 

The floors were designed for a live load of 150 pounds per square foot. 

The girders are 18 inches wide and 28 inches deep and are reinforced with 
seven 1-inch bars, five of these being bent up, three being carried horizontally 
over the supports into the adjacent bay. The floor slab is reinforced with %4- 
inch bars, 7 inches on centers, with two out of every three bars bent up and 
staggered so that exactly as much steel is carried in the top of the slab over the 
supports as in the bottom of the slab in the middle of the span. 

The method of arranging the ducts for the blower system of heating is of 
special interest, these ducts being carried up inside the wall pilasters, so as to 
do away with all unsightly or cumbersome heating equipment. 

In the warehouses the second and fourth floors are designed for a live 
load of 200 pounds per square foot, and the third floor for a live load of 300 
pounds per square foot. For these loadings it was found more economical to 
use two rows of columns instead of a single row—otherwise the construction 
is substantially the same as in the hose building. 

Fig. 56 (p. 126) is a cross section of one of the warehouses and shows the 
details of design and construction for the floor system, columns, walls and 
footings. 


125 









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Fig. 56.—Cross-Section of Warehouse, Boston Woven Hose and Rubber Company. 
(See p. 1283 


126 


Men of Foresight 
sound judgment, and ripe experience 


are most often found directing the en- 
largement of commercial properties. 


@ To such men the advantages 
of reinforced concrete housing are 
bound to appeal. The more 
thoroughly the matter is investigat- 
ed, the more obvious these advan- 
tages become. 


q The success of concrete, however, 
is dependent in some measure on the 
quality of Portland Cement used. 
(‘‘Portland’’ means merely the kznd 
of cement, it does not designate the 
brand which determines relative 


quality. ) 
q Those tamiliar with concrete con- 
struction recognize the somewhat 


i 


unique position of the Atlas Com- 
pany among Portland Cement man- 
ufacturers. Operating the largest 
cement mills in the world, with a 
productive capacity of eighteen mil- 
lion barrels yearly, this Company has 
relied chiefly upon the excellence of 


its product for such gratifying results. 


In consequence, Atlas Portland 
Cement has become generally known 
as ‘‘the standard by which all other 
makes are measured. ”’ 


q As an evidence of the success with 
which Atlas has been used in factory 
erection, we mention a few note- 
worthy examples of the exclusive use 


of Atlas: 


Terminal Warehouse Co., 27th, 28th—W. Eleventh Ave., N. Y. Cit 


Bethlehem Steel Co. ; : So. Hethlioheat Pa. 
Shredded Wheat Co.’s Factory - : : Niagara Falls, N.Y. 
Wheatena Co.’s Factory . Rahway, N. J. 


B. & O. R. R. Warehouse, 26th St. & Eleventh ees cceNe Meptoity 
Puritan Food Products Co. : : Fredonia, N. Y. 





Amalgamated Phosphate Co.’s Plant ; : * Chicora, Fla. 
Wille! Barre Lace Co.’s Plant. ; Wilkes-Barre, Pa. 


Watertown Light & Power Co.’s Power House ; . Watertown, N. Y. 
Republic Rubber Company : : ; Youngstown, O. 
Butler Brothers. Randolph St. Bridge : ‘ : Chicago, ll. 
American Book Co., 22d & Prairie Ave. ‘ . Chicago, Il. 
_ Wabash Railroad Shops Mes Decatur, IIL. 


Firestone Tire & Rubber Co., Compton & Locust isa St. Louis, Mo. 
Roberts, Johnson & Rand Co., 15th & Washington Ave., St. Louis, Mo. 


Medart Patent Pulley Co, 3500 De Kalb St. ; St. Louis, Mo. 
Bettendorf Axle Co. ‘ Peete: Davenport, Ia. 
The Galloway Company . : Sr tes. 2 . Waterloo, Ia. 


q The most cautious buyer cannot 
fail to be impressed by such tangible 
evidences (from among many) that 
Atlas has merited the confidence 
placed in its superiority by those 
whose sound judgment designated 
its use in so many plants. 


q We rest firm in the belief that 
your careful analysis of the facts pre- 
sented will cause your judgment to 
coincide with that of other business 
men—that the use of Atlas is most 
satisfactory in the end. 


HERE is a recognized stand- 
ae ard in every line of business, 
— brand that leads in qualety 
and service. Incement that brand is 
‘Atlas’? because it stands for the 
best there is in unzformity, strength 
and color. | . 

That is why ‘‘Atlas’’ is used 
most in important work and_ is 
known as,— 


“The standard by which all 
other makes are measured” 





In order to provide for the excess compression in the concrete at the bot- 
tom of the girder at the support, the girders were made deeper next to the 
columns by forming a flat haunch. 

The concrete for the floor construction was mixed in the proportions of 
one part Atlas Portland Cement to 214 parts sand to five parts broken stone 
of size to pass a 34-inch ring, while for the columns and pilasters a mixture 
of 1:114:3 was used. 

The stresses assumed in computing the sizes of the various members were 
500 pounds per square inch extreme fibre stress in the members of the floor 
system and 600 pounds per square inch direct compression in the concrete, 
this stress being permissible because of the rich proportions used, and 16,000 
pounds per square inch tension in the steel. Corrugated bars were used 
throughout the buildings. 

All floors were finished with a 1-inch granolithic surface mixed in the 
proportions of I part cement to 2 parts sand and placed within three hours 
after the under slab so as to form one homogeneous slab. 

The roof surfaces were covered with three-ply tar and gravel roofing laid 
directly on the concrete, the roof pitch being 1% inch to a foot. 


Ines GOL ETS 
3-/’berlical Dars. 

















_Llan. L/eva/ion. 


Fig. 57.—Reinforced Footings for Interior Columns. (See p. 127) 


FOOTINGS. 


In the hose building and the warehouses the first floor is placed directly 
on the ground, but the footings for the interior columns and wall pilasters are 
carried down to a solid foundation 14 feet below this level. 

The curtain walls between pilasters in the first story are carried only to 
the level of the outside ground and supported there by reinforced concrete 
beams spanning from pilaster to pilaster. 

Fig. 57 shows the detailed design of a typical interior column footing. 
These footings, reinforced with eight 1-inch bars placed in four layers. 


127 


two of them diagonally, are 7 feet square and of a modified flat truncated 
pyramid type 20 inches deep at the edge and 24 inches at the column. 


REINFORCED CONCRETE PILES. 


The power house is carried on reinforced concrete piles, which were 
formed in horizontal molds above ground and then driven. Fig. 146, chapter 
XX, gives the design of a typical pile and the photograph in Fig. 58 shows 
one of the piles being lifted into position for driving. 





Fig. 58.—Hoisting Concrete Pile into Driving Position. (See p. 128) 


The piles taper from 14 inches at the top to g inches at the point and are 
reinforced with four 74-inch bars connected at intervals, as shown, with %4- 
inch warping bars. The concrete was mixed by hand in proportions 1:2:4, 
using 34-inch trap rock. A 114-inch galvanized iron pipe was cast in the center 
of the pile for a water jet. 

The piles average about 30 feet long and were driven at the age of thirty 
to forty days. The hammer weighed 4,700 pounds and the blows were cush- 
ioned by a head consisting of a plate iron collar 16 inches square on the inside 
and 3 feet in height, encasing an oak block 16 by 16 by 18 inches to the bot- 
tom of which six thicknesses of rope and four layers of rubber belting were 
nailed. The usual drop was 3 feet, but in some cases this was increased to 
1o feet without injuring the pile. 

The average cost of the piles driven was $1.63 per linear foot of pile. 


128 


CONSTRUCTION. 


The construction plant consisted of a 14-yard Ransome mixer with a 
Ransome hoist in a tower. The concrete was conveyed in Ransome carts and 
barrows. All forms were made on the ground and hoisted into place by a 
derrick, which also lifted the steel reinforcement from the ground to its des- 
tination. The forms were used over four times on each building. 

The photograph in Fig. 60 shows one of the warehouses during 
construction. 

The total cost of the buildings was about $270,000. 





Fig. 60.—Warehouse of Boston Woven Hose and Rubber Company During Con- 
struction. 


129 


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130 


CHAPTER XIII. 


BUSH MODEL FACTORY. 


The plant of the Bush Terminal Company, located in South Brooklyn 
on the east shore of New York Bay on Thirty-sixth street, between Second 
and Third avenues, will cover when completed an immense area and comprise 
some hundred and fifty warehouses and factories. Many of the more recent 
of these buildings are of reinforced concrete construction, the factory selected 
from this group for description being 75 ft. wide by 599 ft. long, and six 
stories high above the basement. Several features of the design are of un- 
usual types. 

The Terminal Company owns some 160 acres of land with nearly three- 
quarters of a mile of water front. A number of piers, each one-quarter of a 
mile in length, with wide docks between, permit the largest ocean steamers 
to discharge and load without interference. The large warehouses, 50 by 
150 feet, and from four to seven stories high, provide the steamship lines 
renting the piers with unusual facilities for both storage and trans-shipment 
of freight. 

In addition to this storage and shipping business handled by the piers 
and warehouses, a plan is already being carried out to erect eighteen fireproof 
factories or loft buildings, their floor space to be rented for manufacturing 
purposes. The first of these factories, built in 1905, and the second, called 
the Bush Model Factory No. 2, built in 1906, offer unusually attractive fea- 
tures because of the excellent facilities afforded. The details of the latter, 
which is shown complete in Fig. 61, form the subject of this chapter. 

The builder of this concrete factory was the Turner Construction Com- 
pany. Mr. E. P. Goodrich, formerly chief engineer for the Bush Terminal 
Company, prepared the structural design, and Mr. William Higginson was 
the architect. 


DESIGN. 


Instead of the usual system of beams, girders and slabs, the floors consist 
essentially of heavy girders directly supporting ribbed slabs, designed so that 
the under surface presents a corrugated or ribbed appearance, the purpose 
being to use for the necessarily long spans a minimum quantity of concrete 
placed most effectively to take the loads upon it. 

An idea of the general plan of the structure is gained from Fig. 62. In 
order to present it on a fairly large scale, only one end of the building, a 
length of about 225 feet in a total of 599 feet, is shown. 


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Fig. 63.—Sectional Elevation of Bush Factory No. 2. 


133 


The sectional elevation may be seen in Fig. 63. 

Two lines of columns 16 ft. 7 in. on centers divide the factory into aisles 
about 24 ft. in width, thus giving exceptionally good floor space for either 
storage or manufacturing. Heavy girders run lengthwise of the building 
from column to column, while spanning the distance between these two lines 
or girders and the walls is the ribbed floor system. 

Two groups of four elevators each are located one-quarter way from each 
end of the building, and in adjoining bays on each side of both groups of ele- 
vators are the stair wells. The first floor plan, Fig. 62 (p. 132), shows the 
stairs to the basement only on one side of the elevators, but an additional 
flight is provided for the stories above. Except for the location of the stairs, 
the floor system of the different stories is identical, thus simplifying the de- 
sign and permitting the use of the same forms throughout. 

The roof is surrounded by a fire wall 3 feet 6 inches high. A series of 
skylights over the center aisle afford additional light to the top story. 

Round rods formed into trusses on the ground and raised to place ready 
to drop into the forms provide the reinforcement. The proportions of the con- 
crete used throughout were one part Portland cement, 2 parts sand, 4 parts 
stone, being equivalent in actual volume to one barrel (4 bags) cement, 7.2 
cubic feet of sand, and 14.4 cubic feet of broken stone. The aggregate con- 
sisted of sand excavated by dredges from Cowe Bay, and washed gravel of a 
size passing a 34-inch sieve. 


COLUMNS. 


The column footings are supported by wooden piles, and the area of the 
footing is so large in proportion to the size of the columns as to require a 
special design of heavy horizontal rods and vertical stirrups. 

In Factory No. 1 the interior columns are cylindrical and composed of 
au outside shell of cinder concrete 214 inches thick. These cinder concrete 
cylinders were prepared in advance in 2-foot lengths in a zinc mold, with 
spiral hooping and expanded metal forming the inner surface. After harden- 
ing, they were set one upon another in the building, and filled with concrete. 


In Factory No. 2 the columns are octagonal in shape, and composed 
wholly of gravel concrete. Just below the girders the section was made 
square (see Fig. 65, p. 138), these square caps being the same size on all 
the stories so as to avoid altering the rib and girder molds. 

The columns were spirally reinforced with round high carbon steel 3% to 
Y2 inch in diameter, the pitch varying in the different stories. The loading 
upon the columns was graduated from 500 pounds per square inch of their 
section for the upper floor to 1,000 pounds per square inch in the basement. 
This, however, assumed full loads on all the floors at the same time, which 
would not ordinarily occur, so that the columns in the lower stories are liable 
to be stressed much less than the nominal figures. The spiral hooping is 
computed to assist in bearing the load. 


134 


mii FLOOR SYSTEM. 


The general scheme of design has been referred to in paragraphs above. 
Longitudinal girders of 13 feet 4 inches net span, supported by columns 16 
teet 7 inches on centers, carry the ribbed slabs which run across the building 
with a net span of about 23 feet. 

The details of design of the beams and ribbed slabs are drawn in Fig. 
64. The ribs are V-shaped in cross-section, as shown in Sections aa and bb. 
Two 1-inch round rods, one bent up at the points determined by moment dia- 
gram, and the other extending horizontally to the girders, provide for the 
tension, and 14-inch stirrups are bent around and wired on to the horizontal 
rods. Ribs A, which are shown in the diagram, connect the two girders, 
while ribs B, which run from the girders to each wall, are similar in design, 
except that the upper rod cannot project beyond the support, and is therefore 
anchored by bending it with a quarter turn around another rod which runs 
at right angles to it in the wall. 

The steel is designed for a maximum pull of 16,000 pounds per square 
inch when the full allowed load is on the floor, and stirrups are provided 
wherever the shear exceeds 50 pounds per square inch. The floors are de- 
signed for a loading of 200 pounds per square foot besides the dead weight 
of the concrete. 

The design of the principal girders is also shown in Fig. 64. The stirrups 
are close together at the ends of the girders where the shear is the greatest 
and each stirrup is looped around the tension rods, then passes up on each 
side of the girder and across, as shown in the sections. The stirrups are 1%4- 
inch in diameter near the end of the beam, then at the points where the large 
rods are inclined and thus take a portion of the shear, the size is reduced to 
5/16 inch, and this is continued to the center of the beam, the spacing grad- 
ually becoming wider as the shear decreases. The tensional reinforcement 
in the girders consists of four 1%-inch rods, two of which are bent up just 
beyond the one-quarter points, and extend nearly to the center of the column, 
where each is connected with the reinforcement in the next girder by an oval 
link of 74-inch round steel. 

‘In the bays around the elevators, the rib forms were dropped 8% inches, 
so as to make the slabs between the ribs 12 inches thick, as shown in Section 
CC, Fig. 62. 

No reinforcement was placed longitudinally of the building at right 
angles to the ribs. In the floors first laid with the V-shaped rib, slight shrink- 
age cracks occurred between the ribs and parallel to them. These, however, 
did not open or indicate any structural weakness, and they were eliminated 
by more thorough rodding of the surface. 

The underside of the floor construction, and also the columns, are shown 
in the photograph, Fig. 65 (p. 138). 

The reinforcement was according to the Bertine Unit Girder Frame sys- 
tem as modified by Mr. Goodrich. This work of bending and placing was 


135 


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performed under a separate contract by Mr. M. S. Hamsley in an open shed 
near the building. To the wooden posts supporting the roof of the shed, 
brackets were fastened at the exact locations to support the horizontal and 
the bent-up rods of the truss. These principal members were bent in the 
special bending machine provided for the purpose, then were brought to the 
shed and hung upon the brackets, when the stirrups were sprung upon them, 
and wired to the large rods by ordinary stove pipe wire. The system of rods 
for each rib or girder thus formed a truss, as shown in Fig. 64, and was taken 
by the general contractors, elevated to the floor where it was to be used, and 
dropped into the form. The girder frame or truss rested upon blocks of con- 
crete placed in the bottom of the form, and the rib truss was held upright by 
wiring each end to the steel in the girder truss. 

On the girder trusses, four men worked in a gang, and could put together, 
after the large rods were bent, from twenty-five to thirty frames per day. 

The spirals for the column reinforcement in Factory No. 1 were formed 
around a horizontal skeleton drum by two men who wound the %-inch wire 
around it and wired it to the 14-inch longitudinal rods. In Factory No. 2 a 
special machine was used for bending. 


WALLS. 


The walls consist essentially of glass between concrete columns. The 
window lintels are reinforced concrete beams and above the floor level 8-inch 
walls were carried up from the floor to the window sills, which formed a part 
of the wall and were troweled hard while setting. These low walls were put 
in after the structural part of the concrete was several stories above them, as 
shown in Fig. 67 (p. 140). 

The building is without partitions except around the elevator and stair 
wells. These were built after the floors were completed, and instead of being 
located directly under the beams or ribs they were placed alongside of them, 
slots being left in the floor slab so that they could be poured from the floor 
above directly into the forms built for them. The reinforcement of these 
partition walls consists of 3¢-inch round rods 15 inches apart both horizontally 
and vertically. 

The exterior columns are divided into blocks by horizontal moldings at- 
tached to the inside of the form. After completing the building, the walls 
were given a wash of Lafarge cement. 


CONSTRUCTION. 


Two mixing plants were located in the basement of the building near the 
two elevator shafts. The arrangement of the entire plant was according to 
the Ransome design. Each mixer was located on a platform about 3 feet 
above the floor level, and the raw material supplied to it by wheelbarrows. 
An electric motor supplied the power. The hoist, driven by a separate motor, 


137 


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received the concrete directly from the mixer, and raising it to the floor where 
the concrete was being laid, dumped it into a hopper, from which it was fed 
by a gate into 2-wheel carts and conveyed to place. Each construction plant 
cost in the neighborhood of $2,500. 

The building was completed in seventy-four working days, the average 
progress being 10.4 days per story. During this time 16,000 cubic yards of 
concrete were placed and 950 tons of steel. The usual gang consisted of 80 
carpenters and 180 laborers. 

Fig. 67 illustrates the work in progress on the fifth floor, where the 
column and girder forms are also being set for the floor above. The forms 
and braces are removed from the first, second and third floors, and they are 
being raised from the fourth floor to the floor above by falls carried by a tri- 
angular frame, which is seen projecting above the work. The photograph 





Fig. 66.—View Illustrating Form Construction for Bush Terminal Factory. (See p. 139) 


also shows the bracing and alignment of the faces of the exterior column 
forms. On the second floor the panels below the windows are being poured, 
a part of the forms being still in place. From the panel next to the corner 
and also from the panels of the first story the forms have been removed and 
show the finished surface. The molding of the columns also distinctly 
appears. 

The photograph, Fig. 66, shows the general layout of the forms, the 
girder forms extending lengthwise of the view with the ribs at right angles 
to them. The rib forms, which are approximately triangular, rest directly 
upon the sides of the girder molds, and narrow pieces of plank are dropped 
between them to form the bottom-of the rib. 


139 





(See p. 139) 


Fig. 67—Bush Terminal Factory No. 2 Under Construction. 


The total cost of the building complete was approximately $450,000. It 
has automatic sprinklers, steam heat, ample toilet rooms, heavy freight ele- 
vators, wire glass windows in metal frames, standard automatic fire doors, 
hardwood floors, and so forth, to make really a model factory. 


I4I 


(E¢I *d 22S) 


*A10}98Y IED JOJO psrexyseq—'gg “B14 





142 


CHAPTER XIV. 


PACKARD MOTOR CAR FACTORY. 


The Packard Motor Car Company at Detroit, Michigan, turned out in 
1905 700 automobiles. The demand for these cars necessitated an enlarge- 
ment of the plant, and in the spring of 1906, after careful consideration of the 
various types of construction, it was decided to build the new factory of re- 
inforced concrete. The building illustrated on page 142, Fig. 68, is the result. 

Plans were drawn at once by Mr. Albert Kahn, architect, and the con- 
tract was let to the Concrete Steel and Tile Construction Company, of De- 
troit, the Trussed Concrete Steel Company acting as engineers. 

The structure, as is shown on the plans, is long and narrow, and in the 
form of an L, so that all parts of the floor are well lighted. It is proposed 
at some future time to extend the building by carrying out another wing. 
At present there are two stories, and the roof is designed as a floor with a 
temporary covering, as described below, so that another story can be added 
at a later date. The first floor is laid upon the ground with no basement. 

The building is designed to provide very large floor area without inter- 
ference of columns. A single row of columns runs through the center of the 
factory, and these are 32 feet apart on centers, a distance slightly greater 
than the space between the line of columns and the walls on each side. 

Although a motor car appears to be a heavy machine in itself, the parts 
are comparatively light, and by placing the heavier machinery on the ground 
floor, it was possible to allow a floor load of only 100 pounds per square foot, 
in addition to the dead load or weight of the structure itself. In certain parts 
of the floor, this load is increased, around the elevators especial care being 
taken to give an excess of strength. This comparatively light live load to- 
gether with the type of floor construction selected, a combination of tile and 
concrete, permitted the rather unusually long spans. 

The general plan, Fig. 69, shows the layout of the floor, with an outline 
of the location of the beams, girders and columns. 


FLOOR SYSTEM. 


The first floor is built directly upon the ground. The top soil was re- 
moved and the surface thoroughly tamped, then covered with 6 inches of 
cinders rammed hard to receive the concrete. On top of this porous layer, a 
5-inch thickness of concrete in proportions 1 part cement to 2 parts sand to 
5 parts broken limestone was spread, and covered with a 1-inch mortar sur- 
face, laid before the concrete below had set, in proportions 2 parts cement to 


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3 parts sand, and thoroughly troweled with a steel trowel to a smooth surface. 
This was divided into sections as it was being laid to provide contraction 
joints. 

In the floor above, the wide spacing of the columns, already mentioned, 
necessitated beams and girders of unusual length, and consequently of un- 
usual width and depth. The girders (see Fig. 69) are 30 feet 8 inches in net 
length between columns, or 32 feet 8 inches on centers, and measures 22 inches 
wide by 36 inches deep from top of slab. Each girder supports one beam 
at the center of its span, the alternate beams running directly into the col- 
umns. The reinforcement, which consists of Kahn trussed bars,* is very 
clearly seen in section NN in the figure. The girder selected, as shown on 
the plan below it, is taken at the intersection of the two wings of the building, 
and the column at the right is therefore narrower than the left-hand support, 
the latter illustrating the typical columns in the building. 

The floor system, as already mentioned, is designed for a load of 100 
pounds per square foot in addition to the weight of the concrete and steel. 
The design is figured so that this loading will not produce a tension in the 
steel exceeding 16,000 pounds per square inch, and will keep the compression 
in the concrete everywhere within the limit of 500 pounds per square inch.} 
The proportions of the concrete are one part Atlas Portland cement, 2 parts 
sand, 4 parts broken limestone, the exact measurements being one barrel (4 
bags) cement to 7.56 cubic feet sand to 15.10 cubic feet stone. 

The shear or diagonal tension is provided for by bending some of the 
tension rods and also by the bent-up portion of the individual bars. 

The beams, of which a typical section, MM, is also shown in Fig. 69, are 
27 feet 1 inch net span between girder and wall column. The general con- 
struction is similar to the girder shown above it and labeled beam “B” except 
that fewer bars are bent up because the shear is less. The section of the 
typical beams is 30 inches deep and 18 inches in width. 

A somewhat peculiar slab section is shown in the upper portion of section 
MM. This is made up of sections of tile and concrete placed alternately. 
The floor slab is 14 feet 6 inches net span between beams, and consists es- 
sentially of a series of concrete beams 8 inches deep by 4 inches in width 
spaced 16 inches apart on centers and reinforced with Kahn trussed bars. 
These little beams run directly into the upper surface of the regular beams, 
labeled “A” on the plan, and are supported by them. 

Between these little beams hollow tile is laid, the method of construction 
being to first place the tile upon the level panel form, then set the reinforcing 
metal in position between the rows of tile, and pour the concrete. The ob- 
ject of the insertion of tile is to lighten the floor slab, and thus reduce the 
weight upon the beams and girders by occupying space which must other- 
wise be solid concrete. It also permits very simple form construction, con- 
sisting chiefly of a large plain surface readily built and removed. 


*See Illustration, Fig. 69, page 144. 
{Figured by the parabolic formula, or nearly 600 pounds by the straight-line formula. 


145 


After hardening, the under surfaces of the floors are plastered with 2 
inches of Portland cement mortar to hide the tile and form the ceiling. On 
top of the floor slab, a 2-inch wearing surface of cement mortar finish is also 
laid to make the finished floor. 

The beams around the elevators are specially constructed to sustain a 
weight of 8,000 pounds live or superimposed load, plus 8,000 pounds from the 
counterweights, plus 4,000 pounds, the weight of the elevators loaded. 

The original specifications called for a roofing designed to carry 40 pounds 
per square foot, but it was afterwards decided to build this as a floor of the 
Same construction as the second floor, so that another story could be added 
when required On top of the level surface thus formed, a layer of cinders 
was spread and shaped so as to pitch to sumps; a I-inch layer of mortar was 
laid on the cinders, and upon this tar and gravel roofing. 


LMM. 













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Fig. 70.—Stair Details. (See p. 147) 
146 


COLUMNS. 


The interior columns are in general 24 inches square and designed for a 
safe loading which produces a compressive stress in them not exceeding 450 
pounds per square inch. The concrete was made in proportions one part 
Portland cement to 14 parts sand to 2 parts stone, and reinforced with Kahn 
trussed bars. 

The wall columns are similar in design, but smaller in section and spaced 
16 feet 4 inches apart on centers, so that all the cross beams run directly into 
them. A longitudinal beam at each floor line connects these wall columns 
and also supports the brickwork, which is built up to the level of the window 
sills. 

STAIRS. 


The stair details may be seen in Fig. 70 (p. 146). They consist in general 
of a slab reinforced with Kahn trussed bars and surface, with a 1-inch tread 
of cement mortar. 


CONSTRUCTION. 


The factory was sixteen weeks in building, and in its construction 2,100 
cubic yards of concrete were laid and 225 tons of steel placed. 
The arrangement of the plant is clearly shown in Fig. 71. Two mixing 
























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plants were located as shown, one with a Ransome mixer fed by an automatic 
hoist, and one with a Smith mixer. Each of the mixers dumped into a bucket 
hoist, which elevated the concrete to a bin on the fourth floor, where it was 
placed by wheelbarrows. The work of construction is shown in the photo- 
graph in Fig. 72. One of the concrete hoists is seen on the left, and one of the 
double platform hoists which elevate the tile and steel is on the right. The 
upper surface of the floor slabs, with the alternating concrete and tile, and the 


147 


top surface of the girders and beams are also distinctly visible in the fore- 
ground. The interior of the finished building is presented in Fig. 75 (p. 52): 


FORMS. 


For the forms, 134-inch lumber was used, except that for the floor panels 
No. 1 Norway pine, dressed four sides, was employed. The cost of lumber 
averaged $27 per thousand, but there was a large salvage, that is, a large pro- 
portion of the lumber was suitable for use on another job, because of the 
wide floor slabs and large beams and girders, which cut up the stock less than 
usual. 

Typical form details are drawn in Hig se7 3 paeiso)s lhe clamps or 
brackets of the column forms are driven up with wedges so as to make tight 
and prevent twisting. The beam molds on the right of the diagram are held 
together with iron clamps or braces placed against 2 by 4-inch battens, which 
also serve as supports for the joists which carry the sheathing. 

The centering was erected so that the column forms could be removed 
first, then the sides of the beam molds, and next the floor forms, leaving the 
bottom of the beam molds with the shores in place. These shores were gen- 
erally left in three or four weeks, while the remainder of the forms were taken 
down in two or three weeks. Owing to the length of the span and the heavy 
weight of the beam molds, the bottoms of these were built on the ground and 
then raised to place, and the sides were constructed in position. This avoided 
the elevating of the completed mold. 

Fig. 74 shows the exterior of the building under construction, with the 
column and beam forms and the struts still in place in the second story. 
Some of the first floor shores also remain to support the principal beams and 
girders. The illustration also shows the platform hoist for raising the tile. 

The interior view of the completed factory is shown in the photograph, 


Fig. 75, page 152 


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Fig. 74—Exterior View of Packard Factory Under Construction, Showing Second Floor Center 





(See p. 148) 


Fig. 75.—Interior View of Packard Factory Completed. 


CHAPTER XV. 


WAREHOUSE OF SYRACUSE COLD STORAGE COMPANY. 


The warehouse of the Syracuse Cold Storage Company, Syracuse, N. Y., 
erected during the summer of 1909, illustrates the application and the 
economy of factory-made unit-concrete floors. 

The warehouse is a six-story and basement building approximately 78 
feet square. While it was originally designed for mill construction, alternate 
bids were taken using both a monolith concrete design and a structural steel 
frame incased in concrete with separately molded floor sections. This last 
type of construction was found to be cheaper than either of the others and 
consequently was adopted. 

The photograph in Fig. 76 (p. 154) is an interior view of the completed 
structure. 

The structural frame and floors were manufactured and erected by the 
Onondaga Litholite Company, using the Watson Unit System, under the di- 
rection of Chas. D. Watson, of the Watson Engineering Company. 


DESIGN. 


With the exception of the top floor the building was designed to carry a 
live load of 300 pounds per square foot. The columns were spaced 15 feet 3 
inches on centers both ways. The structural steel frame, which consisted of 
plate and angle columns carrying Bethlehem girder beams, was designed to 
carry the entire live and dead loads, the concrete encasing the columns and 
girders being considered only as fireproofing. 

The separately molded floor sections, details of which are shown in 
Fig. 77, rested on the lower flange of the I beams, reinforcement being pro- 
vided for ties over the top flanges. The connections were filled with field 
concrete placed after the members were in position. 


CONSTRUCTION. 


The concrete floor sections were delivered both by rail and by team 
from the plant at which they were manufactured, three miles distant. The 
concrete members were unloaded by a boom attached to the steel columns. 
They were distributed about the building and set in place, as shown in Fig. 
78 by chain hoists on portable I-beam trolleys. 


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ies: 77.—Details of Separately Moulded Floor Sections. (See p. 153) 


The top flange of one beam in each panel was coped to allow the beams 
to enter, and they were slid into position on the lower flange, wedged up, 
pointed underneath, the projecting reinforcement tied over the top flanges 
and the spaces between the ends and edges grouted in solid. 





Fig. 78.—Method of Handling Separately Moulded Floor Section. (See p. 153) 
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After the separately molded members were in place they were covered 
with a 2-inch granolithic wearing surface. 


COST. 


The table in Fig. 79 gives the detailed cost of the warehouse. As shown 
by this table the separately molded floor sections cost 2014 cents per square 
foot in place, the steel frame and fireproofing 211% cents per square foot and 
the cost of engineering and superintendence about 2 cents per square foot. 
This gives a total of only 44 cents per square foot or 4 cents per cubic foot of 
volume for frame and floor. 


157 






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158 


CHAPTER XVI. 


TEXTILE MACHINE WORKS. 


An unusual type of factory building was erected at Reading, Penn., by 
the Textile Machine Works during the winter of 1904-5 for the manufacture 
of machinery for cotton and woolen mills. Comparatively light, but high- 
speed, machine tools were installed, such as lathes, planers and drills. 

The feature of most interest in the design is the floor system. The 
columns were built in place in the usual way by pouring concrete into wooden 
molds, but, instead of building wooden forms in place for the floor system and 
pouring the concrete into them, all the members were molded separately and 
placed after hardening. The design of the beams and girders also was de- 
cidedly unusual, for to reduce their weight and the quantity of concrete in 
them, the Visintini system was adopted, in which the members are of open 
or lattice work, formed as actual trusses. 

The Visintini system was invented by Franz Visintini, an architect of 
Zurich, Switzerland. Although applied in a number of cases in Europe, this 
building was its first introduction into the United States. 

The Concrete-Steel Engineering Company, of New York, who controls 
the American patents, designed the building and also acted as consulting en- 
gineers during erection. Day labor was employed in the construction, the 
men being directly upon the payroll of the Textile Machine Works. 

The building, which is shown complete in Fig. 80, is 50 feet wide by 200 
feet long and four stories high. Wall columns are spaced 121% feet apart, 
and a center line of columns on the same spacing extends through the center 
of the building. The principal girders, 24 feet long, run across the building, 
connecting the wall and center columns. 


COLUMNS. 


The column footings are not reinforced, but are stepped, as shown in Fig. 
81, and laid in proportions 1:3:6. To assist in transmitting the pressure of 
the columns, which are of richer proportions, 1:2:4, and also to afford a beart- 
ing for the column rods, a 14-inch plate was set 3 inches below the top of the 
footing. After laying the footings, the column reinforcement was placed with 
the longitudinal rods butting directly upon the plate, as shown, and forms of 
dressed white pine were built around them. The concrete of the column was 
then poured in the usual manner. The details of a typical interior and exte- 
rior column are shown in Fig. 81, and in Fig. 82 (p. 161) the columns are illus- 
trated as they appeared with the shoulders for receiving the girders and 


159 


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Fig. 82.—View of Visintini Columns and Girders in Textile Machine Shop. (See p. 159) 


with the rods projecting upward so as to join on the columns in the next 
story above. The center columns in the lower story are 18x18 inches square 
and 15x15 inches for those above. Wall columns are 15x15 inches on the first 
floor and 12x15 inches above. The principal reinforcement in the columns 
through the middle of the building consists of four 14-inch vertical rods in 
the two lower stories, and four 1r-inch rods in the third and fourth stories. 
Three 14-inch Thacher rods* are also inserted in the exterior columns. Occa- 
sional loops of small rods hold the heavier rods in place, and assist in resist- 
ing shear. The ends of the principal rods are planed smooth and they are 
butted and connected with a 6-inch length of pipe sleeve, so that perfect com- 
pression is assured. The outside rows of columns are similar except that the 
rods are differently spaced. The pressure on the concrete is limited to 350 
pounds per square inch. 


FLOOR SYSTEM. 


Running across the building from column to column and 12% feet apart 
on centers are the large Visintini lattice girders 24 feet long. 

In ordinary design these would be connected by floor beams spaced 6 or 
8 feet apart, with slabs between the beams. The Visintini system, however, 
permits the slabs and floor beams to be laid as one; that is, after placing the 
girders the floor beams were laid from girder to girder, but close together so 
as to form a floor slab themselves. For a wearing surface, a maple floor was 
laid upon 2 by 4-inch stringers, which were bolted together at the ends so as 
to tie the floor together lengthwise of the building as well as to form nailing 
strips. Cinder concrete was placed between the strips. 


The details of a typical floor girder, roof girder and floor beam are shown 
in Fig. 83. The girders are shaped like a Pratt truss, a common type used 
in steel bridges, and the computations of stresses were made as in bridge 
design. The bottom chord consists of a slab of concrete reinforced with 3 
round rods to take all of the tension, and the top chord in compression, is 
similarly reinforced. The vertical web members, which are in compression, 
are of plain concrete, while the diagonals are each reinforced for tension with 
rods, whose ends are attached to the rods of the top and bottom chords. 

The floor beams are only 6 inches thick and 12 feet 5 inches long, and 
these, as stated above, also form the slab, being placed close together. They 
are designed and computed like a Warren truss with all of the web members 
inclined at 45°, half of them in tension and half in compression. 

One of the chief advantages of this type of construction already noted 
is in the method of molding the beams and girders so as to reduce the cost 
of forms. In this case the work was greatly facilitated because the building 
was erected in winter. The beams, of which there ure about 2,900, were 
molded on the ground in an adjacent building. The proportions for the beam 
concrete, based on cement loosely measured, were one part Portland cement 





*See illustration, Fig. 112, page 193. 


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to one part sand to three parts stone screenings. The floor beams weigh only 
480 pounds each. 

The cores, which were oiled before placing, were pulled a few hours after 
pouring, and the side and bottom forms were left on for two days, when the 
beams were hard enough to move. After setting about 10 to 30 days longer, 
as needed, they were carried to the building and raised to place. They were 
run on to the first floor of the building, and then raised through an open bay 
to the floor, where they were required by a platform elevator. 

The girders weigh about three tons each, and were molded upon the floor 
immediately underneath their final position, so that they required only to be 
hoisted into place, a distance of 14 feet, which was done by means of a special 
derrick and two strong hoists. 

The proportions were one part Portland cement (measured loosely), 114 
parts sand and 3) parts broken trap rock passing a 13-inch ring. 

To tie the columns together across the building, the floor beams were 
placed with a 5-inch opening between their ends, and this space filled with 
concrete in which was imbedded a rod, as shown just above the cross-section 
of the girder in the lower portion of Fig. 83. 


COST. 

The total cost of the building was about $40,000, divided as follows: 
Concrete materials ace": (ea ee $5,961.66 
lrongandssteel pe en ote 2 eee ene et ee 6,277.46 
93,000 feet. BY MSlumber.s), ©... ee ee 2,514.61 
Excavating. 205) 1a 0 te Ac ate oe eg eee 388.23 
Foundry work’ (castingsfor cores)». 95.4.0) 642.20 
Machine shop work (making all forms)................ 3,295.21 
Carpenter :work js A ee 4,971.83 
Labor molding and pouring concrete.................. 7,919.27 
Labor placing concrete beams......................... 586.35 
Labor (outside of concrete work Proper) tenis. eee oe 2,422.25 
Brick walls, wooden floors and trim.................... 4,000.00 
Total 597052 ts MR ea ee ce ee $38,979.07 


This sum does not include the cost of engineering nor of general expense. 

About 178 tons of steel were used in the reinforcing and the cost of 
bending and placing it was about ™% cent per pound; 3,590 barrels of Atlas 
Portland cement were used, 1,400 tons of stone and 1,495 tons of sand. 

The total cost of the completed building, including the finish, was 7.9 
cents per cubic foot. 


164 


BLACKSMITH AND BOILER SHOP OF THE ATLAS PORTLAND 
CEMENT COMPANY. 


At the plant of the Atlas Portland Cement Company, in Northampton, 
Pa., concrete is used extensively in construction, not only in foundations and 
for the cement storehouses, but also for the floors and walls of the newer 
buildings. 

In 1906 a new blacksmith and boiler shop was built with a 1o-ton crane 
extending from wall to wall and running upon reinforced concrete arched 
beams. The building was designed by the company’s engineer and built by 
day labor. It is shown complete on page 166, Fig. 84. 


DESIGN. 


The shop is 309 feet g inches long, 55 feet 6 inches wide and 31 feet 2 
inches high to the bottom of the roof trusses, this height being necessary for 
the traveling of the crane. 

The plan of the shop is shown in Fig. 85, and the elevations and sections 
in Figs. 86, 87, 88. 

The walls consist of piers 14 feet on centers, with wall panels and win- 
dows between them. These piers are made of heavy section (see Fig. 88) to 
support the crane, and for this purpose they project into the building 23 
inches as far up as the crane runway, and at the top are connected with arches 
which are laid at the same time and form a part of the wall. The arches are 
reinforced with five 34-inch rods spaced 5 inches apart. The crane run is 
shown in section BB, Fig. 86 (p. 168), and also on a large scale in the detail 
above it. An 8-inch by 10-inch yellow pine timber is bolted directly to the con- 
crete beam, and upon this rests the track. The walls between the piers, which 
are dovetailed into them, as shown, are g inches thick. This is somewhat ex- 
cessive, but the extra quantity of concrete may be justified by the low cost 
of materials and the lean proportions of the concrete, which are 1 part cement 
to 4 parts sand to 5 parts gravel. There is no reinforcement in the wall panels 
except directly above the windows. 

Fig. 88 (p. 170) shows a cross-section of the shop with its steel roof 
trusses and an outline of the crane. 


CONSTRUCTION. 


Somewhat unusual methods of construction were employed. The piers 
were first run up to the full height of the building, as illustrated in the photo- 


165 


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graph, Fig. 89.* Then the panel forms were placed, as in Fig. 90, and the 
concrete poured between them. 

The window frames had been set in advance, so that the openings were 
formed in each wall panel as it was poured. The only tie rods which were 
inserted to connect the piers and the wall panels were at the corners of the 
building, where 14-inch horizontal rods 21% feet long were placed every 3 feet 
in height. (See Fig. 86.) 

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Fig. 88.—Cross Section of Blacksmith and Boiler Shop of The Atlas Portland Cement 
Company. (See p. 165) 


Above the foundations of the shop, 792 cubic yards of concrete were re- 
quired, with only 5,570 pounds of steel. In the foundation 460 cubic yards 
were laid in addition. The concrete was mixed by hand, and the usual gang 
consisted of 2 foremen, 17 men mixing, 4 men hoisting, 4 men placing, and 6 





*This photograph and the two which follow it are from a different building of the Atlas plant, but the 
method of construction is the same. 


170 





Fig. §9.—Wall Piers for The Atlas Portland Cement Company Building. (See p. 170) 





Fig. 90>—Panel Wall Forms for The Atlas Portland Cement Company 
Building. (See p. 170) 


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172 


carpenters. The wages for the laborers ranged from $1.20 to $1.50 per day, 
with a $2 rate for the carpenters. The total cost of the concrete in the founda- 
tions and walls was $29,328, which is equivalent to only $4.93 per cubic yard 
of concrete, an exceptionally low price. The cheapness of labor partially ac- 
counts for the low cost. Ordinarily, in building construction with thinner 
walls and higher material and labor costs, the unit price per cubic yard will 
be greatly in excess of this figure. 

The forms, of hemlock lumber, costing $25 per thousand, were dressed 
only on the side next to the concrete. About 19,000 feet of lumber was used 
at a cost of $485, the labor on forms being about $5,500. Although the forms 
were used ten times, the Engineer estimates the salvage for another similar 
job to be about 60 per cent., as the lumber was but slightly injured. 

On the surface of the ground next to the building, a concrete gutter is 
laid to carry off the surface water and the roof drainage. A detail section is 
given in Fig. g2. 





Fig. 92.—Drainage Gutter. 


COAL TRESTLE. 


The coal trestle is supported upon bents of reinforced concrete 13 feet 
apart, resting upon heavy concrete foundations. The piers of each bent are 
20 inches square and capped by a reinforced concrete girder with an arched 
bottom surface. Supporting the track are pairs of channel irons bolted to the 
concrete girders. At intervals in the trestle, diagonal tie rods with turn- 
buckles are placed in two adjacent bays, the rods extending from the top of 
one bent to the bottom of the next, so as to guard against danger from 
longitudinal expansion and contraction of the stringers as well as any longitud- 
inal thrust due to the movement of the trains. 


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174 


CHAPTER XVIII. 


PIERCE-ARROW MOTOR CAR FACTORY. 


In 1906 when the Pierce-Arrow Motor Car Co. of Buffalo, N. Y., was con- 
fronted with the necessity of more extensive and complete manufacturing fa- 
cilities they decided to build a manufacturing plant complete in every detail; a 
plant that by its perfect system of light, heat and ventilation, its safety and . 
freedom from decay, and its fireproofness, would attract and hold the best and 
most desirable skilled workmen. 

After a careful study of the various types of construction reinforced con- 
crete was selected. The satisfaction this material has given the owners is 

























































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Fig. 94—Block Plan of Pierce-Arrow Motor Car Factory. (See p. 176) 


shown by the fact that during the wonderful development of the past four 
years, when the plant has increased from its original size of 325,000 square feet 
of floor space to its present area of 780,000 square feet, all the buildings have 
been constructed entirely of reinforced concrete. 


175 


A block plan of the factory is shown in Fig. 94 (p. 175). The entire plant 
is laid out with the idea of attaining the highest degree of factory economy. 
With this in view the buildings were arranged so that the materials in process 
of manufacture are gradually conveyed toward the Assembly Building, thus 
eliminating all confusion and unnecessary handling. 

The Brazing, Manufacturing, Assembly, the original Body and Motor 
Testing Buildings, the small Garage and the Power House, were built in 1906 
and 1907 of the Kahn system of reinforced concrete by the Trussed Concrete 





Fig. 95.—Interior of Pierce-Arrow Assembly Building. (See p. 177) 


Steel Company, of Detroit, Mr. Albert Kahn associate architect. The exten- 
sion of the Body Building was built in 1909 by the Turner Construction Com- 
pany, of New York, and the Truck Assembly, Storage and Nickel-Plating 
Buildings, New Garage and addition to Boiler Room by the Aberthaw Con- 
struction Company, of Boston, during the years 1909 and 1910. 

Lockwood, Greene & Company, of Boston, Mass., were the engineers for 
the entire plant. 


MANUFACTURING BUILDING. 


The Manufacturing Building is a one-story structure, 205 feet by 4o1 feet, 
covered over its entire area with a sawtooth roof. The extremely careful work 
and accurate inspection necessary in turning out the small pieces that go into 


176 


the mechanism of an automobile require the greatest possible amount of light. 
The sawtooth skylights and the exceptionally large windows made possible 
through the use of reinforced concrete have solved this problem admirably. 

The photograph, Fig. 93 (p. 174), shows the exterior of the Manufacturing 
Building with the Assembly and Body Buildings beyond. 


ASSEMBLY BUILDING. 


The Assembly Building, 122 feet by 4o1 feet in dimensions, is the most 
interesting of the plant from a structural standpoint. Fig. 95 (p. 176) shows 
the interior. Two three-ton cranes travel the entire length of the building, and 





Fig. 96.—Exterior Elevation of Pierce-Arrow Body Building. 


in order to give these a large area of action, the building is divided by a single 
row of columns down the center. This necessitated roof girders spanning 61 
feet and measuring 16 inches wide by 93 inches deep. These were reinforced 
with Kahn bars having a sectional area of 18 square inches. The crane girders, 
that is the beams upon which the crane runs, span 25 feet from column to col- 
umn and are of reinforced concrete, the rails for the traveller being fastened 
directly to the concrete by 54-inch bolts bedded in the concrete. 


BODY BUILDING. 


The Body Building, an exterior view of which is shown in Fig. 96, 
is a four-story structure, 751 feet long and 140 feet wide, built with two wings 


177 





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60 feet wide and a 4o-foot open court between them. It contains two large 
freight elevators, capable of handling the largest type of touring car, one 
smaller elevator and three reinforced concrete stairways, each enclosed in iso- 
lated brick towers projecting out into the court. 


The beam and girder type of construction was used throughout the build- 
ing, a single row of columns 25 feet on centers running through the center of 
the building. 

Fig. 97 (p. 178), illustrating the interior of the Wood-Working Room, is of 
particular interest as showing clearly the method of attaching the heavy 
motors direct to the ceiling and of suspending the shaft hangers, sprinkler 
pipes and electric-light fixtures from the concrete slab. 





Fig. 99.—Interior of Garage. (See p. 180) 


STORAGE AND NICKEL-PLATING BUILDING. 


A different type of design is followed in the Storage and Nickel-Plating 
Buildings, where the mushroom or girderless-floor construction is used. Fig. 
98 (p. 178) is an interior view of the second floor of the Storage Building, and 
illustrates the value of the flat-slab construction in storage buildings, allowing 
as it does complete utilization of all the space from floor to ceiling, without 
interference from beams or girders. 


179 


GARAGE. 


The Garage is a one-story building, 55 feet wide and 139 feet long, with a 
monitor running its entire length. Fig. 99 (p. 179) shows the interior. In or- 
der to have a large unobstructed floor space, in which to move automobiles 
around easily, no interior columns were used in the building and the roof 
girders spanned 55 feet so as to leave the entire floor clear. These girders are 
16 inches wide and 56 inches deep at the center of the building, sloping with 
the roof to 4o inches deep at the wall columns. 





Fig. 100.—Interior View of Pierce-Arrow Engine Room. 


POWER HOUSE. 


The Power House, the interior of which is shown in Fig. 100, is a 
one-story structure, 55 feet wide and 194 feet long, with no interior columns, 


the regular roof and monitor roof being carried by reinforced concrete girders 
spanning 55 feet. 


180 


CHAPTER XIX. 


PACIFIC COAST BORAX REFINERY. 





The distinction of being the designer and builder of the first two rein- 
forced concrete factory buildings in the world undoubtedly belongs to Mr. 
Ernest L. Ransome, of the Ransome & Smith Company. Of these the Pacific 
Coast Borax Refinery at Bayonne, N. J., a few miles from Jersey City, de- 
serves special attention not only as one of the earliest examples of this type 
of construction, but for its notable record in passing through a terrific fire 
without structural injury. Moreover, the fact that it was not erected until 
1897-8 serves to emphasize the marvelous growth in reinforced concrete con- 
struction. 

The time is so recent and reinforced concrete buildings are now so com- 
mon that it is difficult to appreciate the boldness of the conception to ccn- 
struct a 4-story building, to sustain actual working loads of 400 pounds per 
square foot besides heavy machinery even on the top floor, out of a material 
until recently used almost exclusively for foundations, and considered capable 
of resisting only compressive loads. Of course, the principle of steel rein- 
forcement in concrete had been understood for a number of years previous to 
1897. In fact, a house of reinforced concrete was built in Port Chester, N. Y., 
as early as 1871, and a few other similar structures appeared between this 
date and 1897. But with the exception of the factory at Alameda, Cal., 
also designed and built by Mr. Ransome, the Pacific Coast Borax Building 
appears to be, as above intimated, the first attempt at concrete factory con- 
struction. 

While it is not claimed that the design of this factory is in all respects 
typical of the up-to-date concrete factory building as now erected by the 
Ransome & Smith Company and other contractors, many of its features and 
the methods employed in its construction are well worth consideration. 

As built to-day, double walls are not regarded as essential for factories, 
but instead the wall surface is usually taken entirely by windows separated 
by concrete columns which support the floors above. In the floor system, 
slabs of longer span with correspondingly heavier beams are now more com- 
mon, while expansion joints in floors are not usually specified unless the 
building covers an extremely large area. 


DESIGN. 


The main building is 200 feet long by 75 feet wide, and four stories 
high, rising 70 feet above the ground. Connected with this and forming a 


181 


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part of it is a section which was built first only one story high, and then after 
the fire carried up to the full four stories, as shown in Fig. rot. The area of 
ground covered by the combined buildings is 50,000 square feet. 

The plan of the first story is shown in Fig. 102, the junction between the 
four-story and the one-story portion being indicated by the dot and dash line 
AA. In order to show the plan on a large scale, the first floor of the four- 
story building is drawn in full and a part of the one-story portion is omitted 
as indicated by the irregular lines BB. 

The bays in general are 24 ft. 87% inches x 12 ft. 45% inches; the columns 
in the first story are 21 inches square, in the second story 1g inches, in the 
third story 17 inches, and in the fourth story 12 inches. They are computed 
by a maximum compression of 500 pounds per square inch. 

The sectional elevation in Fig. 103 shows the columns and also the column 
footings which are reinforced in the bottom with horizontal rods. The foot- 
ings were designed so that the compression upon the soil, which is of a marshy 
character, should not exceed 2,500 pounds per square foot. 

Fig. 103 also illustrates the construction of the floor system, and, taken in 
connection with a plan of a portion of the second floor in Fig. 102, gives a good 
idea of the type of design. Girders connect the columns which are 12 ft. 45% 
inches on centers. Between the girders and at right angles to them, run the 
concrete floor beams about 3 feet apart and so thin and deep that they re- 
semble timber joists in appearance. As these beams are nearly 25 feet long 
in the clear, a stiffening web crosses them in the middle designed to serve 
the same purpose as bridging in wooden floor joist construction, that is, to 
assist in preventing tendency to buckle under heavy loads. The girders are 
of rather peculiar construction, being made thicker in the panels next to the 
columns so aS to save expense in forms. (See Fig. 102.) 

Originally, the columns in the fourth story of the main building and also 
the roof were of wood, while the one-story part was of similar construction. 
After the fire the wood was all replaced by concrete, as shown in the plans. 
The roofs were then built as reinforced slabs of 12 ft. 45 inches span from 
centre to centre of the beams, the latter being 24 ft. 87 inches long between 
column centres. Still later the roof of the low part formed the floor for the 
second story when this portion of the building was raised to full height, as 
shown in the finished photograph, Fig. 1o1. 

The reinforcement of the beams and girders and stiffeners of the princi- 
pal floors is shown at the lower part of the diagram, Fig. 103. The slabs were 
built of such short span that they received no reinforcement, the depth being 
4 inches in addition to the 1-inch cement finish. 

The floors with the beams and girders were laid as separate panels about 
24 feet square, a vertical contraction joint being carried down through the 
beams on a line with alternate columns; that is, every eighth beam was built 
double. As stated above, it is not now customary to insert contraction joints 
except on extraordinarily large surfaces, the contraction being provided for 
instead by the steel reinforcement in the beams and slabs. 


183 


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The exterior walls were finished by picking the surface with a sharp tool 
which removed the outside skin of cement so as to show the stone and mor- 
tar between and resemble pean hammered masonry. A part of this work was 
done by hand and part with pneumatic hammers. Although a pneumatic 
hammer averaged about 400 square feet in ten hours, while by hand 100 to 
150 square feet was a fair day’s work for a man, the actual cost with the power 
tool was but slightly less than by hand because of the higher grade of men 
required, the extra men for shifting air pipes, etc., and the wear and tear on 
the tools. 





K——-2 1° —— 


Fig. 104.—Molding of Wall Joints.* 


The surface was also divided into blocks by wood moldings nailed to the 
inside of the form. A section of the molding is shown in Fig. 104. 

The stairs are also of reinforced concrete, typical details being given in 
Fig. 105. 











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Fig. 105.—Sketches of Stair Construction. 


PROPORTIONS OF THE CONCRETE. 


The proportions of cement to aggregate in the concrete varied in differ- 
ent parts of the work. For the aggregate, broken basaltic rock brought down 
from the Palisades of the Hudson was chiefly used. The size was limited to 





* Reproduced by permission from Taylor & Thompson’s “Concrete, Plain and Reinforced.” 


186 


particles passing a 2-inch ring, while for much of the work that which passed 
a I-inch ring was employed. The dust was left in the rock and provided so 
much fine material that only a small quantity of sand, averaging not more 
than 10 per cent., was needed. 

The proportions of the footings were 1 part Atlas Portland cement to 
ro parts of this aggregate. The columns were of 1:5 mixture, and the walls, 
floors and stairs of 1:61. 

For imbedding the rods in the bottom of the floor beams a 1:6 mix was 
employed, using very fine stone for the concrete. 

Concrete of 1:614 proportions made into 3-inch cubes gave a compressive 
strength of 900 pounds per square inch at the age of 7 days. 


CONSTRUCTION. 


Construction was begun late in the fall of 1897 and completed in October, 
1898. The usual time per story was 40 to 50 days, whereas now such a build- 


ing would be put up by the same builders at the rate of a story in one or two 
weeks. 





Fig. 106.—Type of Wall Molds. (See p. 188) 


The materials for the concrete included 10,000 barrels of cement and 
nearly as many cubic yards broken stone, the stone being brought in scows 
down the Hudson River and piled near the shed, in which 1,000 bags of 
cement were stored. 

The construction plant was of quite elaborate design. The cement 
having been wheeled from the shed and the stone measured in barrows, both 
materials were dumped into a hopper which discharged into a car. This car 


187 


was hauled by cable through a subway and then up an incline to about 30 
feet above the hopper and about 400 feet distant, where it was automatically 
tipped into a chute leading to the mixer. The mixer, of substantially the 
same type as the Ransome machines now in general use, discharged into a 
trough containing a screw conveyor which delivered the wet concrete to a 
vertical bucket elevator and this hoisted the material to the story where it 
was required, and dumped it upon a platform which held about one cubic 
yard. 

A steam engine operated the car, mixer and elevator, and also ran a 
twisting machine, bolt cutter and two or three other tools. The column 
forms were built in the usual way with vertical boards paneled together, and 
held with clamps surrounding them. The wall forms were 7% inch dressed 
boards, designed in general like Fig. 106. 

These forms, patented by Mr. Ransome in 1885, are still extensively 
used in wall construction. The special feature is the vertical standard made 
of two 1 by 6-inch beards on edge with a slot between, through which pass 
the bolts. By loosening the nut, the plank behind the standards may be 
loosened and the standards raised. The walls were built in sections 4 feet 
high with central cores to form the hollow walls. 

White pine was used for forms, and the salvage on the lumber probably 
did not amount to more than 1o per cent., although by present methods the 
builders usually figure about 30 per cent. 

The total cost of the building was in the neighborhood of $100,000. 


THE FIRE. 


Some four years after completion, in the spring of 1902, the Refinery was 
subjected to one of the most severe fires to which a manufacturing building 
is liable. Although the building itself is of concrete, it contained a large 
amount of wood in the form of partitions, window frames and bins, in addi- 
tion to the wooden roof, and at the time of the fire one room happened to be 
completely filled with empty wooden casks which provided yet more fuel for 
the flames. Some of the material used in the manufacturing process was also 
extremely inflammable. 

To illustrate the heat of the fire, an insurance man called attention to the 
fact that the plank roof was entirely gone, with no charred wood remaining, 
the brass in the dynamos was melted, and at least in one case a piece of cast 
iron was fused into a misshapen mass. A photograph of the melted cast iron 
is shown in Fig. 107. 

This fusing of the iron is especially remarkable since cast iron melts at 
the high temperature of about 2,200° Fahr. The piece appears to be a portion 
of a pulley which was probably located near an opening in the floor through 
which there was a tremendous draft of flame. 

The chief structural damage to the building at the time of the fire was 
caused by the fall of an iron tank which was located on the wooden roof and 


188 





Fig. 107.—Photograph of Cast Iron Melted by the Fire. (See p. 188) 


supported by timbers from the fourth floor. This weight coming suddenly 
upon the floor broke the slab and two or three of the floor beams, but did not 
pass through to the floor below, being caught by the damaged floor. 

In several places throughout the building the concrete had been split off 
by the fire to a depth of %4 to 1 inch, and on one of the exterior walls a few 
cracks showed over a doorway. The total cost of repairs, including the por- 
tion of the floor broken by the tank, was in the neighborhood of $1,000. The 
broken beams were repaired by inserting new concrete in the central portion 
and supporting it by bolts run down through the ends of the beams which 
still remained in place. 

As a result of the fire the structure was completely gutted, nothing 
remaining but the reinforced concrete and a mass of charred wood, with the 
machinery, shafting, dynamos, etc., melted or twisted out of shape. A photo- 
graph taken directly after the disaster before any repairs were made is given 
in Fig. 108. This photograph also presents a very good view of the Refinery 
itself with the main building and the one-story addition. 

In contrast with the durability of the reinforced concrete under the action 
of the fire is a steel tank house adjoining the building. This was built with 
steel columns and roof girders, and the effect of the heat upon the steel struc- 
ture is graphically shown in Fig. 109. 

A photograph of the Refinery, taken in 1907 and shown as Fig. 110 on page 


189 


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Fig. 109.—Effect of Fire Upon Steel Tank House. (See p. 189) 


192 presents one view of the buildings, showing in the foreground the new part 
also built by Ransome & Smith and the older structure in the background. 


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192 


CHAPTER XX. 


DETAILS OF CONSTRUCTION. 


To provide better adhesion or bond between the steel and concrete than 
is given by round or square rods, many types of deformed bars have been in- 
vented, and those most commonly used in the United States are illustrated 
in the pages which follow. Views are also shown of a number of systems of 
assembling the steel or arranging the reinforcement for application to special 
conditions. 

In addition to this digest of systems of reinforcement, a number of photo- 
graphs are presented of details of construction most commonly met with in 
reinforced concrete buildings. In this connection are shown photographs of 
concrete block walls, surface finish for concrete walls, concrete piles, and 
concrete tanks. 


SYSTEMS OF REINFORCEMENT. 


RANSOME TWISTED BARS.—One of the oldest types of reinforcing 
steel is the square twisted bar illustrated in Fig. 111, invented by Mr. E. L. 
Ransome, of the Ransome & Smith Co., and used as long ago as 1894. 





Fig. 111.—Ransome Twisted Bar. 


Twisted bars may be purchased ready to use, or on.a large job may be 
twisted on the work. The number of twists per linear foot depends upon the 
diameter; thus, for 14-inch bars there may be five twists per foot, and for 
1-inch bars one twist per foot. 

In computing cross-section area of steel in reinforced concrete, the 
twisted bars are figured as square bars of the dimension before twisting. 
Twisted bars are employed in the Pacific Coast Borax Refinery and the Bul- 
lock Electric Company shop, described in Chapters IX and XIX. 


THACHER BAR.—The Thacher bar, Fig. 112, was designed and patented 
by Mr. Edwin Thacher, of the Concrete Steel Engineering Company. Round 
bars are rerolled to the shape indicated. Thacher bars are used in parts of the 
Textile building, Chapter XVI. 


193 


CORRUGATED BARS.—The corrugated bar, Figs. 113 and 114, is the 
invention of Mr. A. L. Johnson, of the Corrugated Bar Company. These bars 
are made in both square and round shapes and are rolled from billet stock, 





Fig. 112.—Thacher Bar. (See p. 193) 


medium or high carbon steel. This company has devised a machine fabricated 
beam and girder unit frame called Corr-Bar Units, Fig. 115, which is self- 





Fig. 113.—Corrugated Square Bar. 


centering and collapsible. The normal size and net sections of both the round 
and square corrugated bars are given in the following table: 


AREAS AND WEIGHTS OF CORRUGATED BARS. STANDARD SIZES 


Corru- (Size in inches............ 4 % 4 KB 34 KR al 1k |1\% 
zated Net area in square inches... .06 | .14/ .25| .39| .56| .76 | 1.00 | 1.26 | 1.55 


Squares Weight per foot in pounds.| .22| .49/ .86 | 1.35 | 1.94 | 2.64 | 3.43 | 4.34 | 5.35 





Corru- |Size in inches............ 3% yy %e % 4 % 1 1%/1\% 
gated Net area in square inches..| .11| .19| .25/| .30 


Rounds Weight per foot in pounds.| .38| .66| .86 | 1.05 162 2.06 2.69 | 3.41 | 4.21 
































Fig. 114.—Corrugated Round Bar. 


DIAMOND BAR.—The diamond bar, Fig. 116, is one of the most re- 
cent types of rolled bar and the invention of Mr. William Mueser, of the 


3 UNS 


z aeRO ReTHDoen Poe = 






Aral ae 


wail) 


2 ft vow 8 








Fig. 115.—Corr-Bar Units. 
194 


Concrete Steel Engineering Company. The sizes correspond to those of 
square bars as shown in the following table: 


Areas and Weights of Diamond Bars. 


SiZengerow es os Yin. %in. Yin. Yin. 3%4in. Win. rin. 1% in. 
Area in square inches .0625 .1406 25 39 56 70mm tT. O0m ae t:50 
Weight per foot.... .213 .478 EOS ML 3 2 ee 1 0 Lh 2.007 5.404805 .31 





Fig. 116.—Diamond Bar. (See p. 104) 


KAHN TRUSSED BAR.—The Kahn trussed bar, Fig. 117, invented 
by Mr. Julius Kahn, of the Trussed Concrete Steel Company, is rolled 
with flanges, which are bent up, as shown in the figure, to resist the shear 
in the beam. The Kahn bar is employed in the Packard Building, described 
in Chapter XIV. 


RIB BAR.—The rib bar, another product of the Trussed Concrete Steel 
Company, is rolled with four longitudinal ribs connected at frequent intervals 
by cross ribs so as to form cup depressions between them designed to grip the 
concrete, 

Areas of cross-section of cup bars are made to correspond to square bars 
of the same nominal size. 


PATENTED 


Fig. 117.—Kahn Trussed Bar. 


HAVEMEYER BARS.—The Havemeyer bar, Fig. 118, is the invention 
of Mr. J. F. Havemeyer, of the Concrete Steel Company. It is rolled in both 
square and round shapes. The square bar has a series of projections and de- 
pressions in conjunction with the plain square section of the bar, the projec- 
tions on the sides equaling the depressions on the corners. The round bar has 
projections staggered on alternate faces. Both the round and the square bars 
have the same net sectional area and the same gross weight as plain bars of the 
same nominal size. 





Fig. 118.—Havemeyer Bar. 


195 


SPIRAL TWISTED BAR.—A modification of the plain twisted bar is 
the spiral twisted bar, Fig. 119, rolled by the Buffalo Steel Company. 





Fig. 119.—Spiral Twisted Bar. 


MONOLITH WEBBED BAR.—The monolith webbed bar, Fig. 120, 
made by the Monolith Steel Company, consists of a principal tension member 
with rigidly attached looped web members shipped with the webs lying down 
on the main bar ready to be raised to the required angle on the job. 











Fig. 120.—Monolith Webbed Bar. 
PITTSBURGH STANDARDIZED REINFORCEMENT.—A form of 
unit reinforcement, made by the Pittsburgh Steel Products Company, is shown 
in Fig. 121. The shear bars, which are inclined at an angle of 45 degrees, are 
electrically welded to the bottom and top bars. 


Section GiRDER CONSTRUCTION 
PITTSBURGH STANDARDIZED REINFORCEMENT 


Fig. 121.—Pittsburgh Standardized Reinforcement. 
EXPANDED METAL MESHES 


























Designation. 
Section in A 
pouueresd nape Size of 
mon Gare Strand— § “Fo oa a Feet in Standard Sheets. 
Mesh. 4 Standard | : Pounds. 
| (Stubs). Re ictra Width. 
€16 in. No.18 | Standard .209 .74 4 ft. or 5 ft.x 8 ft. 
34 in, No. 13 Standard 225 .80 6 ft. or 8 ft.x12 ft. 
1% in. No. 12 Standard .207 -70 4 ft.x8 ft. or 12 ft. 
2 {in. No. 12 Standard .166 -56 5 ft. x8ft. or 12 ft. 
3 in. No.16 | Standard .083 -28 6 ft.x8,ft. or 12 ft. 
3) in. No.f10 | Light .148 .50 6 ft.x8 ft. or 12 ft. 
Sierini. No. 10 Standard 178 -60 6 ft.x8 ft. or 12 ft. 
Syepiil, No. 10 Heavy -267 -90 4 ft.x8 ft. or 12 ft. 
Bein, No. 10 Extra Heavy .356 1.20 6 ft.x8 ft. or 12 ft. 





_ LATHING 





Designation. 


SPeCiale Baar 


Diamond No. 24... . 


Diamond No. 26.... 





Gage, 

United 

States 
Standard 








Square 
Size of Sheets in Yards 
Sheets. a Bundle. ina 

Bundle 
18 x96 9 12 
2014x96 9 131% 
22 16x96 9 15 
24 x96 9 16 
27 x96 9 18 
27 x96 9 18 














EXPANDED METAL.—One of the oldest forms of sheet reinforce- 
ment is expanded metal invented by Mr. John T. Golding. 
Sheet steel is slit in a special machine and then pulled out or expanded 





Fig. 122.—Laying Clinton Welded Wire in Decauville Garage, New York. (See p. 198) 


so as to form a diamond mesh. For convenient reference, the standard sizes 
and gages as adopted by the Associated Expanded Metal Companies are 
tabulated on page 196. 


197 


Expanded metal for slab reinforcement is employed in the Lynn storage 
warehouse, Chapter VII. 

CLINTON WELDED WIRE.—Clinton welded wire fabric, made by the 
Clinton Wire Cloth Company, is manufactured in different sizes of mesh and 
different gages of wire. As commonly made, the longitudinal strands are of 
Jarger diameter and closer spacing than the cross strands, the latter being 
chiefly to prevent construction cracks in the concrete. The wires are elec- 
trically welded at every intersection. 


The fabric is furnished in diameters of wire ranging from 1-10 inch to 
3-10 inch, and with spacing between the strands from 2 inches up to 20 inches. 

The laying of the fabric in the Decauville garage, New York, is illus- 
trated in Fig. 122 (p. 197). 


LOCK WOVEN FABRIC OF STANDARD GAGE 




















Distance on Centers. 
Style. | Long Wires. Cross Wires. 
Long Wires. | Cross Wires. 

A No. 10 Gage | No. 9 Gage 4 in. 6 in. 
B No. 8 Gage No. 10 Gage 4 in. 10 in. 
Cc | No. 6 Gage | No. 10 Gage 4 in. 6 in. 
D No. 4 Gage | No. 10 Gage 4 in. 6 in. 
E No. 3 Gage No. 10 Gage 4 in. 6 in. 








IN AV AVAVAVAVAVAVAVAWA' 


WARAIRABAAL 


Fig. 123.—Triangle Mesh Reinforcement. (See p. 199) 





198 


LOCK WOVEN WIRE.—Lock woven wire is made by W. W. Wright 
& Co. It is similar to the welded wire fabric, except that instead of electric 
welding the intersections are bound together by winding them with soft 
wire. The following table gives the various gages and sizes of mesh for 
different styles of fabric: 


TRIANGLE MESH REINFORCEMENT.—Triangle mesh steel-wire 
reinforcement, Fig. 123, manufactured by the American Steel and Wire Com- 
pany, is made with both single and stranded longitudinal or tension members. 
That with the single-wire longitudinal is made with one wire varying in size 
from a No. 12 gage up to and including a 14-inch diameter, and that with the 
stranded longitudinal is composed of two or three wires varying from No. 12 
gage up to and including No. 4 wires stranded or twisted together with a long 
lay. These longitudinals, either solid or stranded, are always spaced 4-inch 
centers, the sizes being varied in order to obtain the desired cross-sectional 
area of steel per foot of width. 


FERROINCLAVE.—Ferroinclave, invented by Mr. Alexander E. Brown, 
of the Brown Hoisting Machinery Company, is sheet metal bent as in Fig. 
127, and spread over or plastered with mortar to form a sheet 13 inches thick. 


HY-RIB.—Hy-rib illustrated in Fig. 124, and made by the Trussed Con- 
crete Steel Company, consists of a steel sheathing with deep stiffening ribs for 
concrete and plaster work. It is a combined unit of reinforcement for center- 
ing studs and lath. 





TRUSS METAL LATH.—A form of slit metal is made by the Truss 
Metal Lath Company, with the strands bent to receive plaster. 

Truss lath comes in sheets ranging from 24 to 30 inches wide and 68 to 
112 inches long, and in three gages. 


TRUSSIT.—Trussit is formed by expanded metal or herringbone lath 
bent to V-shape section, as shown in Fig. 125. It is a self-centering reinforce- 
ment for light concrete roofs erected without forms, solid partitions without 
studding, curtain walls, fences, etc. It is manufactured by the General Fire- 
proofing Company. 


199 


Patented. 





Fig. 125.—Trussit. (See p. 199) 


HENNEBIQUE SYSTEM.—One of the pioneers in concrete construc- 
tion in Europe is Mr. Hennebique, in France, and the system, which still bears 
his name, is shown in Fig. 126. The Maverick Cotton Mills described in 
Chapter VI were built according to this system. 


COLUMBIAN SYSTEM.—The Columbian Concrete Steel Bar Company 
make two types of reinforcing bars rolled from structural steel. One type, 
called the Columbian ribbed steel bar, is made in sizes running from 7% to 5 
inches in depth, and the other, called the Columbian bar, is a modification of 
the ribbed steel bar varying from 3% to 11% inches in depth, is rolled in sizes 
having the same net sectional area and weight as plain square bars. 


CUMMINGS SYSTEM.—A number of reinforcement details have been 
presented by Mr. Robert A. Cummings, as illustrated in Fig. 129 (See p. 203). 

In the illustration at the top of the diagram is shown the Cummings 
method of forming the bent-up bars and attaching them to the tension bars. 
In general the plan is to provide tension bars with ends specially anchored, 
while securely attached to them are small rods horizontal in the middle of the 
beam or girder, or bent up, as indicated, to pass across the top of the beam 
and form inclined inverted U bars or stirrups. The idea is more clearly 
shown in the sketches below of “Arrangement of Steel.” The “Supporting 
Chairs,” placed at the point of the bending up of the rods, are also drawn. For 


200 


the slab steel another type of supporting chair is employed, as illustrated in 
the detail sketch. 

The Cummings hooped column is also shown in the upper sketch, and the 
details of the column reinforcement below. Each hoop is securely attached to 
the upright rods. 














ef 


f 
zp = 


nics 


| 


YT 








Fig. 126—Hennebique System. (See p. 200) 


UNIT GIRDER FRAME SYSTEM.—A type of reinforcement for beams 
and girders, which is built in the shop or in the yard where the building is be- 
ing constructed, is shown in Fig. 130 (See p. 204). This is the unit girder 
frame, manufactured by Tucker & Vinton. 


HERRINGBONE GIRDER BAR AND FRAME.—The herringbone 
bar made by the General Fireproofing Company, consists of a main ten- 
sion member of either square or twisted lug bars to which looped stirrups are 
rigidly attached. The bar is shipped from the shop completely assembled, so 
that the only work required in the field is the bending of the stirrups to the 
proper angle. When a girder frame is desired, as in Fig. 130, it may be easily 
formed by inserting a properly bent bar through the loops and wiring it to the 
shear members. 


201 


GABRIEL SYSTEM.—Details of the Gabriel system, as laid by the Ga- 
briel Reinforcement Company, are shown in Fig. 131 (p. 205). 


ROEBLING SYSTEM.—The Roebling system is employed in connec- 
tion with a structural steel frame of I-beam or girder construction. 

For all flat construction of floors, the reinforcing system used consists 
of flat bars placed upon edge, secured at the ends to the steel beams and 
bridged with bar separators. The object of the edgewise position of the bars 
is the increased protection thus secured to the reinforcing steel. With this 
type of floor the structural steel frame is generally completely encased with 
concrete, 


1 part portland cement 
2 parts sand 


‘Waterproofing felt Concrete 





Ferroinclave 


1 part portland cement 
Concrete; 2 parts sand 
Hair as required 


Fig. 127.—Placing of Ferroinclave Roof. (See p. 199) 


For light roof construction where the steel work need not be protected, 
a continuous slab is built over the beams, reinforced with flat steel bars, 
3-16 by 1% inches, placed edgewise and held in position by spacers, as shown 


in Fig. 132 (p. 205). 


For floor construction the Roebling Company also uses segmental arches 
of cinder concrete laid upon permanent stiffened wire lath centering, or upon 
wood centering which is carried on steel tees and supported by the steel 
I-beams of the floor system, which are generally placed about 7 feet on cen- 
ters. In this system the material is placed upon’ the centering without 
puddling or tamping, in order to obtain a light porous concrete of high fire- 
resisting quality. 


FACTORY MOLDED CONCRETE. 


To eliminate the cost of forms and at the same time to utilize to best 
advantage the strength of the concrete, the plan has been adopted of molding 
in a shop the various members for a concrete house or factory, and transport- 
ing them to the site of the building for erection. A modification of this plan 
is followed in the Textile machine shop, described in Chapter XVI, where the 
columns were built in place, but the girders and floor beams were cast sepa- 
rately by the Visitini System and raised to place. 

The floors of the Syracuse Cold Storage Building, described in Chapter 


202 


XV, were constructed of factory-made concrete members according to the 
Watson Unit System. 

Concrete members made in a factory are subject to the expense of trans- 
portation to the site of the building and to the erection cost, but over against 
this is not only the saving in form construction, but also the economy of 
manufacturing the concrete in a stationary plant where machinery can be 
utilized, the use of light sections with a minimum quantity of material; and 
the advantage of an initial seasoning of the concrete which eliminates danger 
of too early removal of forms by inexperienced contractors. 

In the larger cities where a plant can supply the local demand, this type 
of construction is an economical form of fireproof construction, especially 
for dwellings, apartment houses and small factories. 

A building of separately-molded members lacks the extreme rigidity of 









%y, Coll Lelidorceme/a 








‘ea Cider, Bean 


























PUQLOT IG UL 
Cet) SEB 

































































2 Grrangemmelt OF Tiel 


‘Sa ceeees, alas eae 
Leta of SYpbor tg, Chars: 


for Wah FEL 


- 
’ 
’ 


Lela of Lrd GL Tefrlahn Lous 











he ane 


'~, Mo 
ee ee 


Colt LEMUOecEsnell. 


Fig. 129.—Details of Cummings System. (See p. 200) 


monolithic reinforced concrete construction unless the connections can be 
made positively unyielding, but even with ordinary care it should be possible 
to construct at least as stiff a building as ordinary mill construction with its 
brick walls, timber columns and beams, and plank floors. 

In Europe the Siegwart system of floor construction has been developed 
quite extensively, using for floor slabs a series of adjacent hollow beams 
formed by the use of collapsible cores. 


203 





Fig. 130.—Unit Girder Frame System. (See p. 201) 


The Standard system has been devised and is now being manufactured 
in the United States by the Standard Building Construction Co., of Pittsburgh, 
Penn. The general scheme is to build floors of light weight I-shaped or T- 
shaped joists of reinforced concrete to replace wood joists or reinforced con- 
crete slabs, and rest the ends of the joists upon walls made of vertical inter- 
locking concrete studding or concrete blocks. Columns are formed in the 


GABRIEL SYSTEM 


REINFORCED CONCRETE 


TYPICAL DETAILS 
D_ Horen i; - 


on Gatun 1s contrnucus Mondlttic Construction 
andeateras from Bettam of Adapted fo mech all requirements 
hum te. Ba Z 


Aternatwa Floor Syskms 


Concrete and Tile 
Light Construction 








OME AU SMUR ERASE 
Slab Concrete 
tay Gnstructon. 





Section ale AA 


Fig. 131.—Gabriel System. (See P. 202) 


wall in light construction by filling the hollows between the vertical studs, 
or blocks, with concrete reinforced with steel rods. For heavy buildings the 
floor joists may rest upon monolithic reinforced concrete girders and columns, 
or upon structural steel girders and columns fireproofed in the factory with 
concrete. 












24/4 Slat ar 






” /é "Hat Lar 


s: 
/ée 
MA eZOS 
Fig. 132.—Roebling System. (See ?. 202) 





An important feature of the Standard system is the method of connect- 
ing the individual members. The reinforcement is allowed to project, and is 
mechanically connected after placing. The connection is finally imbedded in 
fresh concrete so as to give strength and rigidity. 


205 


CONCRETE BLOCK WALLS. 


Frequently concrete blocks are cheaper for factory walls than solid con- 
crete, because no forms are required. However, if used in combinations with 
reinforced concrete interior construction or with steel beams, they must be 
securely connected to them with ties, and the compressive strength of the 
blocks carefully figured to see that there is sufficient area of concrete to carry 
the weight. 

In the warehouse at Nashville, Chapter XI, concrete blocks are utilized 
for partitions. 

An example of a concrete block exterior with a reinforced concrete interior 
construction is shown in Fig. 134 (p. 207). This illustrates the Salem Laun- 
dry Building, Salem, Mass., of which Ballinger and Perrot were architects, and 
Simpson Brothers Corporation, builders. This has a reinforced concrete floor 
system and interior columns of solid concrete. The exterior columns are 
hollow blocks with reinforcing rods running through the openings in them 
and surrounded by mortar of the same proportions as the blocks themselves 
so as to form solid piers. 


CONCRETE TILE. 


Concrete tiles are being used for partitions and floors the same way that 
terra-cotta tiles are employed. They are also coming into extensive use for 
the exterior walls of dwelling houses. They lay very true and even, and for the 
better classes of buildings are plastered. 

One of the best patented processes for making concrete tile consists in 
pouring the wet concrete of the consistency of grout into a mold and then by 
means of a steam jacket, which forms a part of the mold, the water is evapo- 
_ rated from the concrete, so as to permit the withdrawal of the tiles from the 
molds within a few minutes. The product is thus as dense and uniform as 
wet mixed concrete and yet very true in shape and size. Plastering adheres 
better than to most other forms of concrete. 

The factory of the Hunter Illuminated Car Sign Company, described in 
Chapter X, is built of concrete hollow tile or, as it is termed, “Tilecrete,” 
manufactured, as described in the last paragraph, under the Pauly Process. 
In this building the tiles are laid up with mortar without any plastering on the 


surface, 
CONCRETE METAL WALLS. 


A type of wall in which the molds also form the permanent reinforcement 
has been designed and patent applied for by Mr. S. H. Lea. Two walls of 
metal lathing are erected and plastered and the concrete poured between them, 
as shown in Fig. 136 (p. 209). 


SURFACE FINISH. 


One of the most perplexing features of reinforced concrete construction 
is to obtain a pleasing exterior finish. In factory construction the appearance 


206 





Fig. 134.—Concrete Block Walls, Salem Laundry. (See p. 206) 


of the building is usually of less consequence than in the case of dwellings, 
and yet the effect must not be distasteful to the eye. 

Plastering on solid concrete or on concrete blocks is unsatisfactory ia 
climates where the temperature in the winter months falls below freezing 
A very thin skin of cement may be plastered on by a skilled mechanic, br 
this is apt to appear streaked and prove unsatisfactory over a large surfa, 
If the surface is broken by moldings or joints this plan can be used with fai 
results. 

An excellent finish, although a somewhat expeasive one, is obtained by 
removing the surface skin of cement which forms against the molds by dress- 
ing it with a pointed hammer of a pneumatic tool. This method is illustratea 
in Fig. 137 (p. 210), and a photograph of the same wall, taken at close range, 
is shown in Fig. 138 (p. 211). 

Another style of finish is obtained by removing the wall forms within 
twenty-four hours and immediately washing the surface. To do this satis- 
factorily the concrete cannot be laid very wet, or the water will run down over 
the completed surface. A similar effect is obtained with acid treatment. 

Another type of finish, which tests of several years in New England have 
shown to be satisfactory if properly applied, is the slap-dash, illustrated in 
Fig. 139 (p. 212), which is a view of the wall of the Lynn Storage warehouse 
built by the Eastern Expanded Metal Company, and described in Chapter VII. 
The wall is first plastered with cement mortar, and after drying the slap-dash 
is thrown on. 


207 


Wire rope for pulling form. 


rope clips. 
ae clamps. 


azn a II 
+. SSSPAPSSAPOOO 

has 

po ee SSSPAAPPS OL 


Bf 


\ 


()-Ap4 POOLOLIZIZZLLL 


Tap of concrere tiling. Ni HMMA 
Ea ee (AAR 


i 
| ‘ly 


8 


SILL 
—_ a 
———— fo 
eee) 











Uj 
7: 


NNN 


AS 


~ 


SN 


S 
WS 


y 4 V9. 
Casr Tron Point DRIVING Fone ALLIGATOR Powr DRIVING FORM. 
OPERATION FINISHED PULE. OPERATION. FINISHED PILE. 





Fig. 135.—Simplex Pile. (See p. 210) 
208 


EXPLANATION. 


Wire Fabric. 
Spacing Bar. 
Vertical Member. 
Separator. 
Horizontal Member. 


OUQNWP, 
on et tl 


A frame of the desired form 
is erected of structural steel and 
covered with wire fabric as 
shown. A coating of cement or 
mortar is then applied to the 
outside of the wire fabric which, 
ope hardening, forms a shell of 
the desired outline, which may 
be filled in with concrete. This 
method of construction does not 
require the use of forms or 
molds, thus effecting a great 
saving in material and labor, 
besides affording a strong, well- 
finished structure. It may be 
employed in building dams, re- 
taining walls, culverts and other 
structures. 


! 












ove 





Fig. 136.—Lea’s Concrete Metal Wall Construction. (See p. 206) 


209 


CONCRETE PILE FOUNDATIONS. 


In certain cases concrete piles are an economical substitute for wood piles 
or deep pier foundations. Four types of patented reinforced concrete piles are 
illustrated in the following figures: 

The Simplex pile, manufactured by the Simplex Concrete Piling Company, 
is constructed by driving a hollow shell with a point to the full depth and 
filling the hole with concrete as the shell is withdrawn. The different proc- 
esses used in driving this pile are shown in Fig. 135 (p. 208). 

The Raymond pile, of the Raymond Concrete Pile Co., is formed by 
placing concrete in a thin steel tube. The tube is driven with a collapsible 
core within it, and the core is then collapsed and withdrawn, leaving the outer 
shell to be filled with concrete. The driving of Raymond piles is illustrated 


in Fig. 141 (p. 213). 





Fig. 137.—Tooling the Surface of Friedenwald Building Walls. 


The corrugated pile, patented by Frank B. Gilbreth, Fig. 142 (p. 214), 
is cast on the ground and driven by a pile-driver with the aid of a water jet. 
The illustration shows a corrugated pile in process of driving for the founda- 
tion of the warehouse for Mr. John Williams, at West Twenty-seventh street, 
New York city. 

The Gow pile, of the Chas. R. Gow Co., Fig. 140 (p. 212), has an en- 
larged footing so as to give it larger bearing, and is formed by washing down 
a tube with a water jet to a firm strata, and then enlarging the bottom of the 


210 


excavation by an expanding arrangement to form the base of the pile. The 
apparatus is withdrawn and the space filled with concrete. 

The pedestal pile patented by the MacArthur Concrete Pile and Founda- 
tion Company, Fig. 143 (p. 215), has an enlarged base providing a greater bear- 
ing. It is formed by first driving a core and cylindrical casing to the required 
depth. The core is then removed and a charge of concrete dumped to the bot- 
tom of the casing, the core then being used as a rammer to compress this con- 
crete into the surrounding soil until the base is about 3 feet in diameter, after 
which the casing is filled to the top with wet concrete. After the pile is formed 
the cylindrical casing is withdrawn from the ground. 

The compressed pile of the Hennebique Construction Company, Fig. 144 
(p. 216) is formed by dropping a heavy steel-pointed weight so as to compress 
the soil laterally and vertically and then filling the resulting cavity with con- 
crete. The concrete is tamped with a rammer, the final result being a sup- 
porting column larger at the base than at the top. 





Fig. 138.—Photograph of Tooled Surface. (See p. 207) 


DRIVEN PILES.—In many cases where too many boulders are not 
liable to be encountered, piles of rectangular or round shape are built hori- 
zontally upon the ground, reinforced with steel rods, and, after setting for at 
least a month, are driven with a pile driver. A special form of cap is re- 
quired to break the force of the ram on the head of the pile. The corrugated 
pile (Fig. 142) is a special type of driven pile. 


2ir 


Prcene sae ny 


*: S eateiaet A 
chapter enemoatwot : pipe y chemise Pile 
werent a 


Chargeeine Macwene 


Deane BOING Oerans 
& oe € - 
Concreré Pr.é with ENLARGEO FOOTING 


SCALE 14°92 COR 


ee CPG are eee 
ei eva ren faneation 





Fig. 140.—Gow Pile. (See p. 210) 


212 





Fig. 141.—Raymond Pile. (See p. 210) 


213 





(See p. 210) 


Ibreth Corrugated Pile. 


i 


Fig. 142.—G 


14 





Fig. 143.—MacArthur Pedestal Pile. (See p. 211) 





Fig. 144.—Hennebique Compressed fare ae puett ) 


The piles used under the power house of the Boston Woven Hose and 
Rubber Company, and shown in Fig. 146, illustrate another type of driven 


pile. 





























24“ GDbar/. 
Secsion. 


Fig. 145.—Details of Chemical Tanks, Pacific Mills Print Works. (See p. 219) 
216 















S “hy 
50 ays 
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Fig. 146.—Detail of Reinforced Concrete Pile, Boston Woven Hose & Rubber Co. 
_ __ (See p. 216) 
217 


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TANKS. 


Reinforced concrete is being used to a large extent for tanks to contain 
liquids. They require careful design to see that there is sufficient steel to 
resist the pressure, and also very careful proportioning and placing of the 
concrete. 

A system of square tanks or vats in the basement of the American Oak 
Leather Company, Cincinnati, is illustrated in Fig. 147. These are 6 feet by 
8 feet and 6 feet deep, with reinforced walls 4 inches thick. They were built 
in groups of six by the Ferro-Concrete Construction Company with specially 
prepared aggregates. These vats, after over a year’s service, have given entire 
satisfaction and show no signs of leakage. 

A system of circular chemical tanks in the Singe building of the Pacific 
Mills Print Works, Lawrence, Mass., is shown in detail by the drawing in 


Fig. 145 (p. 216). 


219 


MISCELLANEOUS BUILDINGS 


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223 





TRADERS’ PAPER BOARD CO., BOGOTA, N. J. 


Curtin Ruggles Co., Engineers and Builders. 


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TANNERY OF WINSLOW BROS. & SMITH CO., NORWOOD, MASS. 


Aberthaw Construction Co., Engineers. 


Dimensions 87 ft. by 87 ft. 


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INTERIOR OF MANUFACTURERS 


(See page 236.) 








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MANUFACTURERS’ FURNITURE EXCHANGE BUILDING, CHICAGO, ILL. 


Dimensions 70 ft. by 170 ft. Wm. Ernest Walker, Architect; Mortimer & Tapper, 
Builders; Condron & Sinks, Consulting Engineers. 








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SELBY LEAD SMELTING PLANT, SELBY, CALIFORNIA. 
Lindgren-Hicks Co., Builders; John B. Leonard, Consulting Engineer. 





COLGATE SOAP FACTORY, JERSEY CITY, N. J. 
Dimensions 85 ft. by 104 ft. William P. Field, Chief Engineer; 
The Concrete Steel Co., Builders. 


237 





SOAP WAREHOUSE OF KIRKMAN & SON, BROOKLYN, N. Y. 
Expanded Metal Engineering Co., Engineers, 


238 


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240 


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243 


MAIN BUILDING MINTERBURN MILLS COMPANY, ROCKVILLE, CONN. 


Frank B. Gilbreth, Builder. 


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ineers 


8 ft. by 294 ft. C. R. Makepeace & Co., Eng 


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N presenting this book to you, we are of the full 
belief that it will be of real value. Below we 
show a comparative statement of relative values. 
These facts are all clearly brought out in the pre- 
ceding pages. The question in your mind resolves 
itself into, whether you—as a prospective builder, 
architect, or engineer—want a building, 
Firstly of: 


Reinforced Concrete Construction, with— 
Lowest final cost (all classes considered) 
Lowest insurance rate (all classes considered) 
Lower initial cost than steel construction 
Perfect Rigidity 
No depreciation, or repairs 
Sanitary 
Maximum Lighting 
Fireproof 

Secondly: 

Steel Cage, Fireproofed, with— 
Highest initial and final cost (all classes considered) 
Medium insurance rate (all classes considered) 
Noticeable vibration 
Fair lighting 
So called fireproof 

Thirdly: 

Slow Burning, or Mill Construction, with— 
Low initial cost (all classes considered) 
High insurance rate (all classes considered) 
Vibration 
Marked depreciation 
Lighting difficulties 


Burnable 


When you have decided by elimination, in favor of 
Reinforced Concrete, take into consideration the 
recognized merit, the indisputable standard of 
quality of 

ATLAS PORTLAND CEMENT 


245 


CEMENT 
LIBRARY 


CONCRETE HOUSES AND COTTAGES. Vols. I. and II, These books contain 
many half-tone cuts (in tint) of photograph, together with floor plans of concrete houses ranging 
in price from $1,000.00 to $450,000.00. 

The houses in these books show a large variety of designs, of several different methods of 
construction. They are not imaginary sketches, but have actually been built, and were designed 
by the best architects in the country, It is the purpose of these books to show what has been 
and can be done in the way of large and small concrete houses, cottages and bungalows, and 
that the illustrations and plans may be of material assistance, not only in planning a future home, 
but in deciding upon the material to be used in its construction. Vol. I, Large Houses; 
Vol. II, Small Houses. Size 10 x 12 inches. 


Copies will be sent, express prepaid, upon receipt of $1.00 per volume. 





CONCRETE COTTAGES, A sixteen-page pamphlet, showing photographs, floor plans 
and specifications for small concrete houses ranging in cost from $1,500.00 to $5,500.00. 
Copies free upon request. 


CONCRETE CONSTRUCTION ABOUT THE HOME AND ON THE FARM. 
The 1912 edition of this book contains!68 pages and over | 50 illustrations showing many new 
and practical uses of concrete about the home and on the farm, besides full directions for making 
and handling concrete also many specifications, sectional drawings, and photographs of the 
smaller constructions many of which you can build yourself. 

Copies free upon request. Cloth-bound copies, 25 cents. 


CONCRETE IN RAILROAD CONSTRUCTION. A text-book for railway engineers, 
containing detailed descriptions, drawings and many photographs of railway constructions in 


which concrete is used. This book will be sent free only to railroad officials and railroad 
engineers. Price, paper, $1.00; cloth, $1.50. 


CONCRETE IN HIGHWAY CONSTRUCTION. A text-book for highway engineers 
and supervisors. It contains complete descriptions, drawings and photographs of every phase of 
highway construction in which concrete plays a part. It is the most valuable book ever published 
on this subject. Sent free only to highway officials and highway engineers. 

Price, paper, $1.00; cloth, $1.50. 
CONCRETE GARAGES. This valuable book should be in the hands of everyone con- 
templating the construction of a garage. It contains photographs of many concrete garages, 


together with sectional drawings and detailed descriptions as to how they may be constructed. 
Sent free upon request. 


ATLAS-WHITE PAMPHLET. This pamphlet tells about Non-Staining Atlas-White 


Portland Cement, its uses, and how to use it. Sent free upon request. 


THE ATLAS Porttann CEMENT CO. 


Book Dept. 30 Broad St., New York 
Daily Productive Capacity Over 50,000 Barrels—Largest in the World 


246 





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‘‘The Standard By Which All i : 
Other Makes Are Measured’? 


ATLAS 


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Dam across the Mississippi } River : i 


